Purification of acyl hydrolase enzymes from the leaves of Phaseolus multiflorus

Acyl hydrolase activities have been purified from the leaves of Phaseolus multiflorus. The purification procedure involved heat treatment, DEAE-cellulose chromatography, Sephadex G-100 filtration and hexyl agarose chromatography. The elution pattern from hexyl agarose columns together with substrate competition experiments indicated the presence of two hydrolase enzymes. The first could hydrolyse oleoylglycerol and phosphatidylcholine while the second would deacylate glycosylglycerides and oleoylglycerol. Overall purification of both enzymes was ca 70-fold and the MW of the glycosylglyceride-hydrolysing enzyme was in the range 70–78000.     

Catabolism of sulphoquinovosyl diacylglycerol by an enzyme preparation from Phaseolus multiflorus

An enzyme which will deacylate sulphoquinovosyl diacylglycerol (SQDG) has been partially purified from the leaves of runner bean (Phaseolus multiflorus). No monoacyl intermediate was observed and the acyl hydrolase was more active towards unsaturated molecular species of SQDG than towards saturated species. The major peak of activity of SQDG acyl hydrolase, separated on both DEAE-cellulose and Sephadex columns, also contained galactolipid acyl hydrolase activity. The distribution of these activities together with substrate competition and inhibitor experiments indicated that at least part of the SQDG acyl hydrolase activity was due to an enzyme that also hydrolysed galactolipids.     

Subcellular localization of lipoxygenase and lipolytic acyl hydrolase enzymes in plants

The subeellular localization of two lipid-degrading enzymes, lipolytic acyl hydrolase (LAH) and lipoxygenase (LOX) was studied. In potato tubers the ac     

Membrane-degrading enzymes in the leaves of Solanum tuberosum

When homogenates of potato leaves were prepared under conditions which are typical for organelle isolation (pH 7.5 and 4°), membrane lipids underwent rapid hydrolysis (17% of phosphatidylcholine was hydrolysed in 2 hr). Leaves of 41 potato cultivars were surveyed for phospholipase activity to determine whether certain cultivars might be more suitable for the preparation of organelles. Phospholipase activities ranged from 1.04 to 11.60, μmol/min · g fr. wt and p-nitrophenyl palmitate hydrolase activity ranged from 0.0119 to 0.0502,μmol/min · g fr. wt. These phospholipase values were several hundred-fold higher than previously reported for potato leaves and nearly as high as in potato tubers. Most of the phospholipase activity in leaves was soluble and not membrane-associated as previously reported.     

Enzymic formation of carbonyls from linoleic acid in leaves of Phaseolus vulgaris

Homogenization of Phaseolus vulgaris leaves at acid pH results in the evolution of hexanal, cis-3- and trans-2-hexenal. With cell-free extracts of leaves, linoleic and linolenic acids are enzymically converted to their hydroperoxides (predominantly the 13-hydroperoxide isomers) and to hexanal or hexenal respectively. Activity was highest in young, dark-green leaves and was stimulated by Triton X-100. Oleic acid is not a substrate for these reactions. Both 9- and 13-hydroperoxides were cleaved to carbonyl fragments and are proposed as intermediates in the formation of volatile aldehydes and non-volatile ω-oxoacids in P. vulgaris leaves. Properties of the enzyme systems are described.     

Arabinogalactan from Phaseolus atropurpureus leaves

Water-soluble polysaccharide material comprising d-galactose (53·0%), l-arabinose (33·2%) and d-glucuronic acid (13·8%) has been isolated from the leaves of Phaseolus atropurpureus. Acid hydrolysis, periodate oxidation and methylation have indicated a highly branched structure. The principal interglycosidic linkages have been tentatively identified as 1,3- and 1,6-linked d-galactopyranose and 1,3-linked l-arabinofuranose residues. In synthesising polysaccharide with these structural features, P. atropurpureus differs from other legumes such as soybean, lucerne and Centrosema.     

Starch synthesis in isolated Phaseolus vulgaris chloroplasts

Isolated bean (Phaseolus vulgaris) chloroplasts were used to investigate the mode of synthesis of transitory amylose and amylopectin from ADP-glucose. Pulse chase experiments showed that labelled glucose in amylose decreased when chased with cold substrate as compared to controls. A significant portion of this decrease appeared in the amylopectin fraction indicating that amylopectin was formed from amylose. However, time course experiments showed that the rate of amytopectin synthesis is higher than that of amylose at the early stages of incubation, suggesting a certain degree of independent synthesis of the two fractions. High concentration of citrate increased the rate of amylopectin synthesis.     

Characterization of an enzyme from Phaseolus vulgaris seeds which hydroxylates GAi to GA8

Hydroxylation of gibberellin-[³H] A₁ (GA₁-[³H]) to GA₈-[³H] by the 95000 g supernatant fluid from imbibed bean seeds required Fe²⁺ or Fe³⁺ and O₂ but was insensitive to CO. The hydroxylating enzyme has a sedimentation coefficient of 4·5 S, and was precipitated by (NH₄)₂SO₄ at 35–60% saturation. This hydroxylase was specific for GA₁ and did not hydroxylate either pseudo-GA₁-[³H] or 16-ketoGA₁-[³H]. Virtually all hydroxylase activity was localized in the cotyledons.     

Wax ester formation catalysed by isoenzymes of lipolytic acyl hydrolase

Wax ester formation by esterification of a long chain fatty acid (palmitic acid) with a long chain fatty alcohol (octadecanol) was enzymically catalysed by acetone dried powder preparations of potato tubers. The enzyme responsible for wax ester formation had multiple isoenzymic forms and was identical with lipolytic acyl hydrolase, a lipid deacylating enzyme. Tubers from different varietiees of potato (Solanum tuberosum) demonstrated markedly different levels of activity and electrophoretic patterns for both wax ester formation and lipid deacylation.     

Induction of tannin acyl hydrolase (EC 3.1.1.20) activity in some members of fungi imperfecti

The potential of gallotannin, methyl gallate, gallic acid, and pyrogallol to induce tannin acyl hydrolase (EC 3.1.1.20) activity in Aspergillus niger, Aspergillus fischerii, Fusarium solani, and Trichoderma viride has been investigated. The maximum induction ratios recorded were A. fischerii (26.7), F. solani (26.1), and T. viride (40.7) when the fungi were induced with gallotannin, gallic acid, and methyl gallate, respectively. A. niger was devoid of basal enzyme activity. The gallotannin tolerance limits for A. niger, A. fischerii, F. solani, and T. viride were determined by progressively increasing the gallotannin concentration and were found to be 20, 4, 3, and 3%, respectively. F. solanii induced with 3% gallotannin has been recommended for the production of tannase enzyme.     

Isolation of legumin-like protein from Phaseolus aureus and Phaseolus vulgaris

An 11S seed globulin has been isolated from Phaseolus aureus and P. vulgaris by zonal isoelectric precipitation and the MWs of the constituent subunits determined. The protein of P. vulgaris occurs in the protein body fraction and its chemical composition, including the N-terminal amino acids and amino acid composition has been determined. The similarity between the 11S globulin of the two Phaseolus spp. and legumin from other leguines is discussed.     

Effect of diethylpyrocarbonate and sodium deoxycholate on polyribosomes from cotyledons of Vicia faba

Degradation of rRNA during the isolation of polyribosomes in the presence of either sodium deoxycholate or diethylpyrocarbonate gave breakdown products with MW corresponding to 1·13, 1·02, 0·93, 0·79, 0·61, 0·52, 0·44, 0·42, 0·30, 0·28, 0·24, 0·20 and 0·12 x 10⁶ daltons.     

Replacement of Mg2+ by polyamines in the aminoacylation of tRNA from Phaseolus

The ability of putrescine, spermidine and spermine to replace Mg²⁺ ions in the charging reaction of tRNA was estimated for seventeen amino acids. The polyamines promoted only the transfer reaction in the case of Leu, Ile, Val, Tyr and Arg. A synergistic effect was observed when spermine was added to a suboptimal concentration of Mg²⁺ (charging at only 5% of the optimal level). This synergistic effect was not observed for Ala, Asp-NH₂, His, Lys and Ser. Kinetic studies showed a slower aminoacylation rate in those experiments when spermine and Mg⁺² (at 5% of the Mg²⁺ optimal concn) were used together than with Mg²⁺ (at the optimal concn) alone.     

Isoenzymes of lipolytic acyl hydrolase and esterase in potato tuber

Five varieties of potato (Solanum tuberosum) were shown by gel- and free-flow-electrophoresis to exhibit multiple forms of lipolytic acyl hydrolase (LAH) and esterase enzymes. The electrophoretic patterns of LAH and esterase activities and protein differed with the variety and were characteristic for a given variety. In the variety (Golden Wonder) with the highest LAH activity (p-nitrophenylpalmitate as substrate), this was 200-fold greater than the esterase activity (p-nitrophenylacetate as substrate) and isoenzyme patterns for both enzymes were the most complex. In the variety with a very low LAH activity (Désirée), the LAH and esterase activities were similar and more simple isoenzyme patterns for these enzymes were observed.     

Epoxidase/epoxide hydrase activity in cell cultures of Phaseolus vulgaris

The presence of epoxidase and epoxide hydrase enzymes in cell suspension culture of Phaseolus vulgaris is demonstrated. Results indicate high levels of enzyme activity using stilbene and stilbene oxide as substrates.     

Protein-polysaccharide linkages in glycoproteins from Phaseolus vulgaris

Serine and hydroxyproline participate in protein-polysaccharide linkages in hydroxyproline-poor glycoproteins from Phaseolus vulgaris cv Pinto. Most substituted hydroxyproline residues contain arabinose, galactose and glucose, but some have arabinose only. Serine residues contain arabinose, galactose and glucose.     

Invertase and auxin-induced elongation in internodal segments of Phaseolus vulgaris

A close positive correlation was observed between segment elongation and the specific activity of soluble acid invertase in stem segments of P. vulgaris incubated for 21 hr in the presence of IAA or of several synthetic auxins and auxin analogues. Optimum concentrations for the stimulation of growth and invertase activity were similar and varied from 10^?6 M (2,4-D) through 10^?5 M (IAA, IBA, α-NAA, β-NAA) to greater than 10^?4 (IPA, PoAA, trans-cinnamic acid). The weak activity of trans-cinnamic acid, a competitive inhibitor of auxin action, may have resulted from cis-trans isomerization during incubation. The concentration of hexose sugars in the segments fell during incubation in the presence of auxin, the greatest decline in hexose concentration occurring in the presence of compounds exhibiting the greatest stimulation of growth.     

Isoflavonoids from Phaseolus coccineus

After treatment with CuCl₂, the following isoflavonoids have been isolated from the runner bean, Phaseolus coccineus: daidzein, genistein, isoprunetin, 2′-hydroxygenistein, phaseoluteone, 2′-hydroxydihydrodaidzein, isoferreirin, kievitone, cyclokievitone, glycinol, phaseollidin, phaseollin, demethylvestitol, phaseollinisoflavan, 2′-hydroxyisoprunetin and 7,4′-dihydroxy-5,2′-dimethoxyisoflavanone. The latter two compounds are novel natural products.     

Variation in low molecular weight carbohydrate composition of Phaseolus vulgaris seeds

Variations in the low M_r, carbohydrate composition have been observed in wild forms of common bean (Phaseolus vulgaris) seed. In four of 23 samples, verbascose content in the seeds was quite high and the ratio verbascose—stachyose was more than 1.0. This type of carbohydrate composition was named type A, and has a much higher verbascose content and lower galactinol and stachyose content than the rest of the wild forms, named type B. Although the total and individual carbohydrate content, with the exception of the verbascose content, of the cultivated forms of the common bean were higher than those of wild forms, the carbohydrate composition of the cultivated forms was essentially similar to type B of the wild forms. This carbohydrate composition was considered to be basic to the species.     

Hormonal control of sterol biosynthesis in Phaseolus aureus

Naphthalene acetic acid increased the sterol content of mung bean hypocotyl sections mainly in the zone of elongation growth. The increased sterol synthesis can be explained by a stimulated conversion rate of cycloartenol into sterols. During the 20-hr incubation period the stigmasterol: sitosterol ratio increased considerably.