Optical rotatory dispersion and circular dichroism of benzoyl polysaccharides

Measurements of optical rotatory dispersion (ORD) and circular dichroism (CD) were made in the range of 400–205 nm for polysaccharide tribenzoates such as 2,3,6-tri-O-benzoyl amylose (I), 2,3,4-tri-O-benzoyl dextran (II), tri-O-benzoyl pullulan (III), 2,3,6-tri-O-benzoyl cellulose (IV), 2,3,6-tri-O-benzoyl mannan (V), and polyglycan dibenzoates such as 2,3,-di-O-benzoyl amylose (VI), cellulose (VII), and mannan (VIII). All compounds exhibit Cotton effects in the region of their UV absorption bands (206–285 nm). Comparison of the corresponding di- and tribenzoyl polysaccharides shows a qualitative agreement in number, position and sign of the CD bands but differences in ellipticity magnitude. The disubstituted derivatives exhibit smaller amplitudes than the trisubstituted ones. The contribution of the C(6) chromophore (linked by a CH₂-group to the asymmetric C(5) atom) was determined to be of the same sign as the combined contribution of the C(2) and C(3) substituents. The CD bonds of the individual polysaccharide derivatives, which differ in number, sign, and position, were discussed in terms of the steric position of the single chromophores and the steric arrangement and interaction caused by the configuration of the polysaccharides. The optical behavior of these polysaccharide derivatives was found to be not strongly influenced by a definite chain conformation in solution.     

Far ultraviolet optical activity of saccharide derivatives. I. Xylan and cellulose acetates

Optial rotatory dispersion (ORD) and Circular dichroism (CD) spectra of several β-1,4 xylan and cellulose acetates and some of their oligomers were investigated. The CD spectra proved considerably superior in terms of information content and interpretability. Comparison of the xylan and cellulose acetate series which also included partially substited cellulose acetates showed that the sign of the CD of the C(6) acetyl was negative. Likewise, the combined contribution of C(1) and C(4) to their equatorially substituted acetyls was positive (with C(1) definitely Positive) and the combined contribution of C(2)_eq and C(3)_eq negative. The solution conformations of both polysaccharide acetates appeared to be random. The CD of White birch xylan acetate which is substituted on the average at every tenth residue with a 4-O-methyl glucuronic acid substituent, was sensitive to it. The xylan oligomer series also illustrated that CD may be used to determine the degree of polymerization of these oligomers up to about 20.     

Total optical activity of agarose: relation to observable transitions in the vacuum ultraviolet

The changes in optical activity that accompany and characterize the coil-helix and helix-coil transitions of agarose in aqueous solutions and gels have been investigated by combined quantitative analysis of data from vacuum ultraviolet circular dichroism (VUCD) and optical rotary dispersion (ORD). VUCD of agarose in the high-temperature coil state shows a single accessible Gaussian band centered at ～183 nm. In the helix state this band is blue-shifted by ～9 nm, and the intensity is increased by a factor of ～2.6. Spectra at intermediate temperatures can be fitted to within experimental error by linear combination of coil and helix spectra, the relative proportions required providing an index of the extent of conformational ordering. ORD spectra throughout the conformational transition have a common form and differ only in absolute magnitude. The temperature course of conformational ordering derived from ORD intensity is in close agreement with the values obtained from VUCD. In both the coil and helix states the accessible VUCD band is positive, while the overall ORD is negative, indicating strong negative CD activity at lower wavelength. The ORD contribution corresponding to the positive VUCD band was calculated by Kronig–Kramers transform, and it was subtracted from the total ORD to give the residual ORD from all other optically active transitions of the molecule. In both the coil and helix states, this residual ORD could be fitted to within experimental error by a single Gaussian CD band at ～149 nm. A negative band at this wavelength has been reported previously for agarose films, but the observed intensity, relative to that of the lower energy positive band, is substantially smaller than the fitted value under hydrated conditions. In both the coil and helix states the total optical activity of agarose, characterized by observed ORD spectra, can be matched to within experimental error by Kronig-Kramers transform of the 149-nm negative band and the smaller positive band at higher wavelength, with no necessary involvement of deeper-lying transitions. The significance of this conclusion for fundamental understanding of carbohydrate optical activity is discussed.     

Molecular motions of polysaccharides in the solid state: dextran, pullulan and amylose.

Dextran, pullulan and amylose have been investigated by differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical and dielectric spectroscopy over a wide range of temperatures and frequencies. No melting or glass transition is seen below the range of thermal degradation (about 300 degrees C) for either amylose or pullulan; only dextran shows a Tg at 223 degrees C (delta cp = 0.40 J/g deg). The viscoelastic spectrum of the 'dry' polysaccharides is characterized by a low temperature relaxation that occurs at -94, -73 and -59 degrees C, at 1 kHz, (activation energy 32, 39 and 52 kJ/mol) in dextran, pullulan and amylose respectively and is assigned to small entity local motions of the polysaccharide backbone. Absorbed water strongly modifies the relaxation spectrum, inducing a new relaxation below room temperature and dissipation regions associated with water loss above room temperature. The former appears at temperatures higher than the relaxation characteristic of the dry polymer and moves to lower temperature with increasing water content. In normal 'room humidity' conditions (about 10% absorbed water) the water-induced relaxation, attributed to the motion of complex polymer-water relaxing units, is the only observable feature in the dynamic mechanical and dielectric spectrum below room temperature.     

Optical properties of sugars. VI. Circular dichroism of amylose and glucose oligomers

The CD spectra of amylose, the maltose oligomers, cellobiose, and the cyclodextrins are measured in aqueous solution to 1640 Å. Two bands are found in this region. An examination of chromophorically equivalent but conformationally different glucans demonstrates that the CD of glucans is sensitive to conformation. However, the conformation of the subunits in the maltose oligomer series appears independent of chainlength. The conformations of the interior maltosyl groups of this series are all approximately equivalent. A comparison of the amylose and cycloamylose spectra indicates that amylose is substantially biased in its chirality. Since there is little chainlength dependence, the oligomers should have a similar chirality bias. The butanol complex of amylose, which is believed to have a V-form helical conformation, has a CD similar to free aqueous amylose. This is consistent with conformational calculations on amylose which predict that the maltosyl subunits of amylose are restricted to a small region on its conformational map which includes the V-form helix. It is also consistent with the idea that amylose a loosely wound and extended helix in aqueous solution.     

Solution studies on heme proteins. Circular dichroism and optical rotation of Glycera dibranchiata hemoglobins

Circular dichroism (CD) and optical rotatory dispersion (ORD) spectra of several liganded derivatives of the monomer and polymer hemoglobin components of the marine annelid, Glycera dibranchiata were measured over the wavelength range 650--195 nm. The differences observed between the monomer and polymer components for the heme dichroic bands in the visible, Soret and ultraviolet wavelength regions seem to result from changes in the heme environment, geometry and coordination state of the central heme iron in these proteins. Within the Soret region, the liganded derivatives of the monomer hemoglobin exhibit predominantly negative circular dichroic bands. The heme band at 260 nm is also absent for the monomer hemoglobin. The ORD and CD spectra in the far-ultraviolet, peptide absorbing region suggest also differences in the alpha-helix content of the monomer and polymer hemoglobins. The values for the single-chain G. dibranchiata hemoglobin are in the expected range (about 70% alpha-helix) as predicted by the X-ray structure of this protein. The lower estimates of the alpha-helix content for the polymer hemoglobin (approx. 50%), may reflect the differences in amino acid composition, primary structure and polypeptide chain foldings. Changes in oxidation state and ligand binding appears to have no pronounced effect on the helicity of either the monomer or polymer hemoglobins. The removal of the heme moiety from the monomer hemoglobin did result in a major decrease in its helix content similar to the loss of heme from myoglobin.     

Conformation of amylose in aqueous solution: Optical rotatory dispersion and circular dichroism of amylose–iodine complexes and dependence on chain length of retrogradation of amylose

The dependence on chain length of two characteristic properties of amylose, i.e., retrogradation and complex formation with iodine, have been studied by using enzymatically synthesized, homodisperse amyloses. The association rates of amyloses in water containing 5% dimethyl sulfoxide have a sharp maximum at a degree of polymerization P?_n of 80; shorter and longer molecules are much more soluble. The iodine complexes of amylose exhibit a strong Cotton effect in the range of the long-wave absorption maximum (position depending on chain length) and two weaker Cotton effects at 480 and 350 nm. The long-wave Cotton effect is most intense at about P?_n 50 and decreases rapidly for shorter and longer chains. This behavior is unexpected and is not in accordance with the further increase of λ_max and λ_max. The experiments can best be interpreted by assuming well ordered, stiff chains in the low molecular weight range (P?_n 50–80). For longer chains, the findings are discussed in the light of current concepts of amylose conformation in aqueous solution, namely the model of the broken helical chain (alternating stiff helical segments and unordered regions) and the model of a flexible coil without a significant helical content. However, according to the results given in this paper, a wormlike helical chain seems to be the most adequate model for amylose conformation in neutral solution.     

Phage T4 lysozyme. Physical properties and reversible unfolding.

Phage T4 lysozyme has been used extensively in studies of the genetic code. However, little work has been done on the characterization of the purified enzyme. Therefore, we determined the spectral properties of native T4 lysozyme and used these properties to follow the unfolding transition. The ultraviolet absorption spectrum and solvent perturbation difference spectrum indicate that the aromatic amino acids are extensively exposed to solvent. The CD and ORD spectra are characteristic of a high fraction of helix. Guanidine hydrochloride denaturation results show that over a T4 lysozyme concentration range of 0.07-1 g/l the c-m equals 2.7 M guanidine hydrochloride at pH 5 and that the transition is 100% reversible as judged by enzymatic assay and four different spectrophotometric criteria: CD at 295 nm, CD at 223 nm, fluorescence intensity at 350 nm and wavelength of maximum fluorescence. Guanidine hydrochloride denaturation at pH 2.5 was followed using fluorescence emission and has a c-m equals 1.7 M guanidine hydrochloride, indicating a strong pH dependence of chemical unfolding. Reversible thermal denaturation conditions were located at acid pH, 0.2 M NaCl, 10-4 M dithiothreitol and 10-6 M T4 lysozyme. The CD signal at 223 nm was used to measure the unfolding. Thermodynamic analysis of the thermal data showed an increase in T-m, increment H-unf and increment S-unf with increasing pH.     

Effect of counterions on the conformation of hyaluronic acid.

To study the effect of metal ions on the conformation of hyaluronic acid, circular dichroism (CD) and optical rotatory dispersion (ORD), along with viscosity measurements of the Na, Li, Ca, and Mg salts of the polymer, were carried out. With divalent cations, the results show a decrease in CD minima at 210 nm and an increase in ORD troughs at 220 nm, as compared to monovalent ions. To account for this behavior, the ORD in the visible range corresponding to the observed CD bands was directly calculated from the Moscowitz equation using Kronig-Kramer's transform. The background rotation was found to be more levorotatory in bivalent than in monovalent cations. The ORD spectra of various metal hyaluronates differ significantly from each other in the far ultraviolet region, especially at lower pH values. The values of intrinsic viscosities of these hyaluronates, on the other hand, are almost the same in the pH range of 1–3. These results indicate a local conformation variation rather than any appreciable change in the chain conformation of the molecule in the presence of different counterions.     

Conformational studies of bacterial polysaccharides. II. Optical activity of some bacterial capsular polysaccharides

The optical activity of the Klebsiella capsular polysaccharides of serotypes K1, K5, K6, K8, K11, K56, and K57 has been studied in aqueous solution. Measurements of ORD in the range 185–450 nm reveal anomalous ORD with Cotton effects near λ₀ = 195nm. The results are evaluated quantitatively according to hte Moffitt-Yang and the Drude equations. Straight lines are obtained in the Moffitt-Yang plots, while the corresponding Drude plots yield bent curves. The b₀ values, calculated from the slope of the stright lines in the Moffitt-Yang plot, range from 90 to 270 and suggest a helical superstructure for the capsular polysaccyharides. Positive b₀ values have been found for K1, K5, and K6 and negative b₀ values for K8, k11, K56, ad K57. Circular dichrosim has been mesured, but the CD curves are found to be truncated at the lower-wavelength end due to the 185-nm limit of the spectrometer used. Measurements of the temperature dependence of the specific optical rotation [α] reveal in all cases cooperative order–disorder transitions at temperatures, T_m, fro m298 to 323°K. The van′t Hoff enthalpies derived from the width of the transition curves are found to be similar in value to those of polypeptieds in aqueous solution. The K8 polysaccharide shows a two-step transition. The results are discussed in relation to the known primary structure and x-ray data from oriented and partially crystalline films. A model is suggested for the two-step transition in the K8 polysaccharide.     

Studies on pig serum lipoproteins. V. Optical properties of low density lipoproteins.

The circular dichroism (CD), optical rotatory dispersion (ORD), and fluorescence emission spectra of two subfractions of pig serum low density lipoproteins (LDL1 and LDL2) were compared. The contribution of the carbohydrate moiety to the CD and ORD spectra was estimated on the basis of data obtained from isolated glycopeptides and the constituent monosaccharides. The carbohydrate moiety had no effect on the conformation of the protein moieties of LDL1 and LDL2 (apoLDL1 and apoLDL2). However, the intensities of the observed extrema in the CD and ORD spectra of the glycopeptides were greater than those expected from the monosaccharide composition. This suggests the existence of secondary structure in the carbohydrate moiety. In contrast to the carbohydrate moiety, the contribution of the lipid moiety to the CD and ORD spectra could not be neglected. When the effect of the lipid moiety was subtrated from the CD and ORD spectra, the spectra due to apoLDL1 and apoLDL2 were quite similar. Delipidation in the presence of sodium dodecyl sulfate (SDS) induced an increase in the content of disordered structure and alpha-helix accompanied by a decrease in the beta-structure. In the presence of SDS, marked quenching occurred in the fluorescence emission spectra with a blue shift of the maximum emission wavelength from 332 to 326 nm. ApoLDL1 and apoLDL2 showed quite similar SDS-induced conformational transitions. The secondary structures of apoLDL1 and apoLDL2 in the native lipoproteins were stable to changes of pH and temperature. However, this stability was lost in the presence of SDS. These results suggest the importance of the lipid moiety in maintaining the native secondary structures of LDL1 and LDL2. From the overall similarity of the optical properties of apoLDL1 and apoLDL2, we conclude that the secondary structures of apoLDL1 and apoLDL2 are identical.     

Temperature dependence of the optical activity of human serum low density lipoprotein. The role of lipids.

Low density lipoprotein (LDL) (1.024-1.045 G/cm3) was prepared by ultracentrifugal flotation from serum of normal fasting subjects. Circular dichroism (CD) and optical rotatory dispersion (ORD) spectra in the ultraviolet region were measured at 2, 25, and 37 degrees on LDL, lipid extracted from LDL, and on pure component lipids. All exhibit reversible, temperature-dependent optical activities. Sphingomyelin has a strong negative CD band around 195 nm. Cholesterol and cholesteryl esters have a CD minimum at 208 nm. They have positive CD bands around 201 and 198 nm which decrease sharply and become negative at 198 and 193 nm, respectively. The CD of the total lipid extract of LDL is negative and drops monotonically below 200 nm. Thus, the lipid moiety could account for the increasing negativity of the CD of LDL below 195 nm. After subtraction of the ellipticity corresponding to amounts of lipids in organic solvents equivalent to those found in LDL, the 208-210 nm trough of LDL diminishes markedly. This is accompanied by a blue-shift of the extrema from 195-196 to 193 nm and an increase in the magnitude of the positive ellipticity. The fractions of helix and of beta form in the protein, determined by the method of Y. H. Chen, J. T. Yang, and K. H. Chau ((1974), Biochemistry 13, 3350), in the wavelength interval of 250-240 nm, remain essentially unchanged between 2 and 37 degrees. These observations suggest that a substantial part of the thermal change in the CD spectrum of LDL between 208 and 210 nm may be attributable to lipids.     

Far ultraviolet optical rotatory properties of poly-L-tryptophan. I

A block copolymer [γ-Et-DL -Glu]_m [L -Trp]_n was prepared using N-carboxy anhydrides (NCA) of L -tryptohan and γ-ethyl DL -glutamate. The block copolymer, dissolved in trifluoroethanol (TFE)–dichloroacetic acid (DCA) mixtures, exhibited a sharp change in the specific rotation at 546 mμ when the solvent composition reached 70–75% DCA content. Optical rotatory dispersion (ORD) and circular dichroism (CD) measurement were carried out in TFE solution in the spectral range 180–350 mμ. Indole side-chain chromophores were found to be optically active in the polymer. On the other hand, these groups exhibit very small optical activity in the model compound C₆H₃? CH₂? O? CO? (L -Trp)₂? O? CH₃. Indole groups therefore appear to be in a dissymmetric environment only in the polymer. From these data it was concluded that poly-L -Trp is in some type of helical conformation in TFE. Strong overlapping of CD bands from side-chain chromophores and peptides chromophores in the wavelength range 185–240 mμ does not allow definite conclusions to be drawn about the type of helical conformation which exists in poly-L -Trp in TFE solution.     

Free will and evolution

The circular dichroism (CD) and optical rotatory dispersion (ORD) spectra of a suspension of arbitrarily shaped optically active particles may be calculated by using the Rayleigh-Debye theory. Subject to restrictions on the size of the particles and the refractive index of the suspending medium the CD and ORD spectra of the suspension are the same as the intrinsic molecular spectra. The size of the particles can be comparable to or larger than the wavelength of the incident light provided that the optical properties of particles and medium are sufficiently similar. Therefore, it should be possible to experimentally reduce scattering artefacts in CD and ORD spectra of suspensions by suitably choosing a medium in which the particles are suspended.     

Helical conformation of amylose in aqueous solution. I. Viscosity measurements

Two amylose samples, amylose V (DP_w = 2300) and amylose HE 15 (a low-substituted hydroxyethylamylose, DP_W = 1600) were studied. The intrinsic viscosity of the polymers in aqueous solution was measured with regard to its dependence on the alkalinity (0 to 5MNaOH), the ionic strength (0 to 5M), and the temperature (0 to 75°C). Additionally, the temperature dependence of the viscosity of the amylose-iodine complex was measured. It was found that the two amylose samples show the same dependence on the studied parameters. Therefore, it was concluded that the conformation is unchanged by the hydroxyethylation in the present case. In a discussion, steric, hydrodynamic, and thermodynamic data on amylose in solution are compared with the corresponding data on cellulose and dextran. The comparison leads to the conclusion that amylose in a neutral solution must have a helical conformation, corresponding to the well-accepted rod conformation of cellulose. The helical conformation also explains several viritual anomalies in the behavior of amylose. The results of the experiments support the helix model for amylose. The conclusion of the whole work, therefore, is that the amylose molecule in neutral aqueous solution can be regarded as a random coil, built up by helical segments. The average number of monomers per segment exceeds 100. This value decreases with increasing alkalinity.     

Helical conformation of amylose in aqueous solution. II. Electron spin resonance,fluorescence depolarization,and sedimentation measurements

In the previous study [Elmgren, H. (1984) Biopolymers 23, 2525–2541] concerning the conformation of amylose in aqueous solution, it was stated that amylose in a neutral aqueous solution is a random coil consisting of helical segments. In terms of Kuhn statistics, each segment contains more than 100 monomers. The number of monomers per segment decreases by alkali addition. In an attempt to verify these statements, a combined electron spin resonance (esr) and ultracentrifugation (uc) study of a weakly hydroxyethylated amylose sample in water and alkaline solvents was performed. This combination of measuring techniques makes it possible to estimate the Brownian motion, and thus the mass of the polymer segments. As a control for the obtained esr data, fluorescence depolarization (fdp) measurements were performed on the polymer sample in a bicarbonate buffer at pH 10. The result of the study confirms that the amylose segments are very heavy in water. In strong alkaline solvents, the segment mass corresponds to that of a few monomers. Our findings thus support the statements made in the preceding article, and the data obtained by others. [Kitamura S., Yunokawa H., & Kuge T., (1982) Polym. J. 14, 85–91; Kitamura S., Yunokawa H., Mitsu'ie S., & Kuge T., (1982) Polym J. 14, 93–99].     

Theoretical pi-pi absorption, circular dichroic, and linear dichroic spectra of collagen triple helices

Absorption, CD, and LD spectra of the π-π* transition near 200 nm are calculated for poly(Gly-X-Y) (X,Y = Gly, Ala, Pro) in four conformations proposed for collagen like triple helices in the recent literature. A dipole interaction model is used with the same optical paramenters as in previous studies of polypeptide spectra. The CD spectra are sensitive to backbone structure and amino acid composition, although the experimentally observed negative peak near 200 nm is a general feature of most the calculated spectra. Interchain interactions significantly affect the CD spectra in most cases. Calculations for (Gly-Pro-Ala)₃ and (Gly-Ala-Pro)₃ in the triple helical structure of Fraser, MacRae, and Suzuki [(1979) J. Mol. Biol. 129 , 463–481] show absorption, CD, and LD spectra in fairly good agreement with experiment. The characteristics of the π-π* normal modes responsible for the calculated spectra are compared with those of the component bands resolved from the experimental spectra of collagen by Mandel and Holzwarth [(1973) Biopolymers 12 , 655–674].     

Crystal and molecular structure of V-anhydrous amylose

The conformation and crystalline packing of V-anhydrous amylose has been investigated by a combination of linked atom model building and X-ray diffraction analysis. The unit cell, the P2₁2₁2₁ space group, the left-handed sixfold helical conformation with all O(6) in gt rotational positions, and the intrahelical O(2)---O(3) and O(2)---O(6) hydrogen bonds are substantially in agreement with previous studies. A new model for packing of the chains in the unit cell and the presence of crystallographic water is proposed. Packing appears to be stabilized by corner-to-center chain O(2)---O(2) hydrogen bonds. The nature of the transition from the amylose–DMSO complex to V_a-amylose was considered and it is shown that the transition involves translation of the amylose chains parallel to the a and b unit cell axes with only slight changes in the orientation of the helix. No significant conformational changes result from the transition.     

Solvent‐dependent conformation of amylose tris(phenylcarbamate) as deduced from scattering and viscosity data

The z‐average mean‐square radius of gyration 〈S²〉_z, the particle scattering function P(k), the second virial coefficient, and the intrinsic viscosity [η] have been determined for amylose tris(phenylcarbamate) (ATPC) in methyl acetate (MEA) at 25°C, in ethyl acetate (EA) at 33°C, and in 4‐methyl‐2‐pentanone (MIBK) at 25°C by light and small‐angle X‐ray scattering and viscometry as functions of the weight‐average molecular weight in a range from 2 × 10⁴ to 3 × 10⁶. The first two solvents attain the theta state, whereas the last one is a good solvent for the amylose derivative. Analysis of the 〈S²〉_z, P(k), and [η] data based on the wormlike chain yields h (the contour length or helix pitch per repeating unit) = 0.37 ± 0.02 and λ^?1 (the Kuhn segment length) = 15 ± 2 nm in MEA, h = 0.39 ± 0.02 and λ^?1 = 17 ± 2 nm in EA, and h = 0.42 ± 0.02 nm and λ^?1 = 24 ± 2 nm in MIBK. These h values, comparable with the helix pitches (0.37–0.40 nm) per residue of amylose triesters in the crystalline state, are somewhat larger than the previously determined h of 0.33 ± 0.02 nm for ATPC in 1,4‐dioxane and 2‐ethoxyethanol, in which intramolecular hydrogen bonds are formed between the C?O and NH groups of the neighbor repeating units. The slightly extended helices of ATPC in the ketone and ester solvents are most likely due to the replacement of those hydrogen bonds by intermolecular hydrogen bonds between the NH groups of the polymer and the carbonyl groups of the solvent. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 729–736, 2009. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

High amylose mutants of rice,Oryza sativa L.

Summary Five mutant lines of rice with increased amylose content in starch granules were identified among floury endosperm mutants. The amylose contents of the mutants ranged from 29.4% to 35.4% and were about twice as high as that of the normal counterpart. Starch properties of the high amylose mutants were analyzed by column chromatography, X-ray diffractometry, photopastegraphy and scanning electron microscopy. The high amylose mutants produced longer unit chains of amylopectin than those of the normal counterpart as well as an increased amount of amylose. A X-ray diffractogram of starch in the mutant was characterized by a type B pattern, while that in the normal counterpart showed a type A pattern which is typical for starches of common cereals. The temperatures at the initiation of gelatinization of the mutants were much higher than that for the normal counterpart. The endosperm cells of the mutant were loosely packed with irregular round-shaped starch granules, whereas those of the normal counterpart were densely packed with polyhedral starch granules. Judging from the results obtained, it was concluded that starch properties of the high amylose mutants of rice were similar to those of the amylose-extender (ae) mutant of maize.