Ribonuclease H from rat liver. II. Partial purification and characterization of cytosol ribonuclease H1.

We have detected in rat liver cytosol three enzymes (termed C-1, C-2, and C-3) which cleaved the RNA moiety of RNA-DNA hybrid. These enzymes were separated from each other by DEAE-Sephadex and Sephadex G-200 chromatography. C-1 and C-2 specifically act on the RNA moiety of RNA-DNA hybrid, while C-3 degrades single-stranded RNA as well as the RNA of the hybrid. The molecular weights of C-1, C-2, and C-3 are about 110,000, 35,000 and 110,000 daltons, respectively, and their activities are absolutely dependent on divalent cations such as Mg2+ and Mn2+. Cleavage by C-1 and C-2 is endonucleolytic, producing mostly oligonucleotides and a small amount of mononucleotides which possess 3'-hydroxyl termini. It seems likely that C-2 is originally present in the nucleus and is released into cytosol because of its loose binding to the nuclear components. As for biochemical properties, C-1 is very similar to the cytosol ribonuclease H initially reported by Roewekamp and Sekeris, and C-2 is very similar to the nuclear ribonuclease H reported by us in the preceding paper.     

A high-resolution c.p.-m.a.s. 13C-n.m.r. study of solid-state cyclomaltohexaose inclusion-complexes: Chemical shifts and structure of the host cyclomaltohexaose

High-resolution, solid-state ¹³C-n.m.r. spectra were obtained for several crystalline cyclomaltohexaose inclusion-complexes. The resonances of C-1, C-4, and C-6 of the host were dispersed. The averaged ¹³C shifts of these resonances were in good agreement with the ¹³C shifts observed in solution, where the dispersion due to conformational diversity is expected to be averaged by rapid interconversion of the conformers. This result indicates that the most plausible source of the solid-state ¹³C-shift dispersions of the resonances of C-1 and C-4 is the diversity of conformations about the glycosidic linkage. The molecular origins of conformation-dependent ¹³C shifts are discussed.     

Isotope-edited 1D and 2D n.m.r. spectroscopy of 13C-substituted carbohydrates.

Three isotope-edited n.m.r. methods have been applied to selectively 13C-substituted monosaccharides and nucleosides to simplify their spectra and/or measure 1H-1H, 13C-1H, or 13H-13C spin-couplings detected via the labeled site. 1D INADEQUATE spectra allowed the selective detection of the natural-abundance carbons that are spin-coupled to the labeled carbon, and adjustment of the mixing time permitted further discrimination between one-bond and longer-range 13C-13C coupling pathways. Geminal and vicinal 13C-1H coupling constants were determined from the analysis of 1H-1H COSY cross-peaks for those protons coupled to the labeled carbon. Long-range 13C-(HETCOR) and 1H-detected (HMBC) 13C-1H chemical-shift correlation spectra permitted the selective observation of those protons coupled to the labeled site, and JH,H values were measured from data projections. The implications of these methods for structural studies of more complex systems is briefly discussed.     

Multiple molecular forms of human plasma butyrylcholinesterase. I. Apparent molecular parameters and broad pattern of the quaternary structure (author's transl)]

Apparent molecular parameters (molecular weights, sedimentation constants, partial specific volumes, free electrophoretic mobilities and isoelectric points) of the four molecular forms C-1, C-2, C-3 and C-4 of human plasma butyrylcholinesterase (EC 3.1.1.8) have been demonstrated by polyacrylamide gel electrophoresis methods and centrifugation in sucrose gradient. The C-1 component is the monomeric form of the enzyme )Mr = 84 800 +/- 5800). All the forms are partially interconvertible and C-1, C-3, C-4 are size isomers corresponding to the monomer, dimer and tetramer of the enzyme. An estimation of the general shape of these forms attempted from electrophoretic and hydrodynamic parameters suggests that they are prolate ellipsoids. The C-4 component in which the axial ratio is at least equal to 8 appears to be arranged as a dimer of dimers (C-3)2 in which the two units are associated in a quasi-linear fashion. The C-2 component is composed of C-1 associated with an inactive smaller subunit, which is responsible for its specific electrical properties (mobility and isoelectric point).     

Genomic insight into Chryseobacterium turcicum sp. nov. and Chryseobacterium muglaense sp. nov. isolated from farmed rainbow trout in Turkey

Four strains, designated as C-2, C-17^T, C-39^T and Ch-15, were isolated from farmed rainbow trout samples showing clinical signs during an investigation for a fish-health screening study. The pairwise 16S rRNA gene sequence analysis showed that strain C-17^T shared the highest identity level of 98.1 % with the type strain of Chryseobacterium piscium LMG 23089^T while strains C-2, C-39^T and Ch-15 were closely related to Chryseobacterium balustinum DSM 16775^T with an identity level of 99.3 %. A polyphasic approach involving phenotypic, chemotaxonomic and genome-based analyses was employed to determine the taxonomic provenance of the strains. The overall genome relatedness indices including dDDH and ANI analyses confirmed that strains C-2, C-17^T, C-39^T and Ch-15 formed two novel species within the genus Chryseobacterium. Chemotaxonomic analyses showed that strains C-17^T and C-39^T have typical characteristics of the genus Chryseobacterium by having phosphatidylethanolamine in their polar lipid profile, MK-6 as only isoprenoid quinone and the presence of iso-C_15:0 as major fatty acid. The genome size and G + C content of the strains ranged between 4.4 and 5.0 Mb and 33.5 – 33.6 %, respectively. Comprehensive genome analyses revealed that the strains have antimicrobial resistance genes, prophages and horizontally acquired genes in addition to secondary metabolite-coding gene clusters. In conclusion, based on the polyphasic analyses conducted on the present study, strains C-17^T and C-39^T are representatives of two novel species within the genus Chryseobacterium, for which the names Chryseobacterium turcicum sp. nov. and Chryseobacterium muglaense sp. nov. with the type strains C-17^T (=JCM 34190^T = KCTC 82250^T) and C-39^T (=JCM 34191^T = KCTC 822251^T), respectively, are proposed.     

Turnover of rod photoreceptor outer segments. I. Membrane addition and loss in relationship to temperature

Membrane turnover in outer segments of Rana pipiens red rods (ROS) was studied in tadpoles maintained under cyclic lighting (12L:12D) at 23 degrees, 28 degrees, and 33 degrees C. Large fragments (greater than 2 microns in diameter or length) were shed from the ROS tips shortly after the onset of light. These were phagocytized by the pigment epithelium (PE) which caused an increase in the number of phagosomes greater than 2 microns in size (large phagosomes). Large phagosomes were present in highest numbers 2-4 h after light exposure and were degraded by 8-12 h. The proportion of ROS that shed each day after the onset of the light cycle increased with increment increases in temperatures (23 degrees C-18%, 28 degrees C-33%, 33 degrees C-42% per day), resulting, in a reduction in the average interval of time between repeated sheddings (23 degrees C-5.6 days, 28 degrees C-3 days, 33 degrees C-2.4 days) though the average numbers of disks shed from ROS at the various temperatures were not significantly different (23 degrees C-139.5 +/- 5.7, 28 degrees C-129.4 +/- 7.6, 33 degrees C-129.9 +/- 4.8 disks/shed packet). Phagosomes in the PE that were less than 2 microns in diameter (small phagosomes) were present in relatively constant numbers throughout the day, and their numbers increased at higher temperatures. The absence of a concomitant increase in small phagosomes as large phagosomes were degraded indicates that large phagosomes were not the major source of small phagosomes. When the PE was isolated to culture in the absence of the retina, these small phagosomes were degraded. The rate of disk addition to the ROS base was determined by autoradiography after [3H]leucine injection. The number of disks added per day increased with elevations of temperature (23 degrees C-32.4; 28 degrees C-55.9; 33 degrees C-65.5). The average number of disks added to the ROS between repeated sheddings (23 degrees C-181.4; 28 degrees C-167.7; 33 degrees C-157.2) was greater than the number of disks shed after light exposure. Inasmuch as the ROS show no net increase in length during the tadpole stages utilized, the remaining disks must be lost at some other time. Electron microscope analysis revealed the presence of small groups of disks in curled configurations at the tips of ROS, suggesting possible stages of detachment.(ABSTRACT TRUNCATED AT 400 WORDS)     

Structure and thermal interconversion of cyclobilirubin IX alpha.

One of the two main photoproducts in bilirubin metabolism during phototherapy in neonatal hyperbilirubinaemia is (EZ)-cyclobilirubin. However, it has not yet been possible to come to a final conclusion as to its chemical structure, despite the fact that much effort has been expended on the problem. The present paper demonstrates that (EZ)-cyclobilirubin is formed by the intramolecular cyclization of the C-3-vinyl group with the position at C-7 rather than at C-6, without delta-lactone-ring formation. The evidence comes from 13C-n.m.r. spectra, which indicate that an oxygen-bound quaternary carbon atom is not present, and from 1H-n.m.r. spectra, which indicate that the orientation of the methyl group at C-2 is equatorial; these findings are supported by mass spectra. The existence of both an epimeric relationship at C-7 between (EE)- and (EZ)-cyclobilirubins A and B and of steric isomers of the hydrogen atom and methyl group at C-2 is supported by the fact that the methyl-group protons at C-2 and C-7 are observed as a paired signal in 1H-n.m.r. spectra, and that new signals at C-7, C-2 and C-3 beta appear in 13C-n.m.r. spectra, that mass spectra of (EZ)-cyclobilirubins A and B are extremely similar and that, furthermore, thermal interconversion between (EE)- and (EZ)-cyclobilirubins A and B is observed.     

Differences in steroid specificity for rat androgen binding protein and the cytoplasmic receptor.

Two proteins in the rat, androgen binding protein (ABP) and the cytoplasmic receptor (CR), have high affinity and limited capacity for binding androgens. To determine the structural requirements for binding with high affinity, each protein was partially purified and the ability of over 100 steroids to compete with [3H]dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one) for binding sites was assessed. The results indicate marked differences in the steroid specificities of the two proteins. Some alterations of dihydrotestosterone at C-2 or C-2 and C-3 increase binding to ABP two to four-fold. Similarly, the affinity of 17 beta-hydroxy-7 alpha-methyl-4-estren-3-one for ABP increases two-fold when a double bond is created at C-14. Addition of a methyl group in the alpha position at C-7 or C-17, or an ethinyl group at C-17 cause little change in affinity; however, modifications at C-11 and C-17 beta, and deletion of the methyl group at C-10 significantly impair binding to ABP. Binding to the CR is maintained or increased by deletion of the methyl group at C-10. Binding is lessened by modifications at C-3 and C-17 beta. Most alterations at C-2, C-7, C-11, and C-17 alpha have only minor effects on binding to the CR. These studies should provide a molecular basis for predicting the effects of specific structural modifications. When some modifications at C-2 or C-2 and C-3 are combined with changes at C-17 beta, the resulting steroids retain very high affinity for ABP and very limited binding to the CR. Such steroids may provide a means for assessing the function of ABP.     

产氢菌Enterobacter sp.和Clostridium sp.的分离鉴定及产氢特性

在高温水体中分离得到2株具有较高产氢活性的微生物菌株Z-16和C-32。根据两菌株的16SrDNA序列分析,初步鉴定菌株Z-16为Enterobactersp.,菌株C-32为Clostridiumsp.。研究了起始pH值、反应温度、碳源等对菌株放氢活性的影响。菌株Z-16的最适产氢条件为:反应系统起始pH7·0,反应温度35℃,以蔗糖为产氢底物。在最适条件下,菌株Z-16的氢转化率为2·68molH2/mol蔗糖。菌株C-32的最适产氢条件为:反应系统起始pH8·0,反应温度35℃,以麦芽糖为产氢底物。在最适条件下,菌株C-32的氢转化率为2·71molH2/mol麦芽糖。以葡萄糖为碳源时,菌株Z-16和菌株C-32的氢转化率分别为2·35和2·48molH2/mol葡萄糖。     

The conformation of abscisic acid by n.m.r. and a revision of the proposed mechanism for cyclization during its biosynthesis.

The n.m.r. spectrum of abscisic acid (ABA) formed from [1,2-13C2]acetate by the fungus Cercospora rosicola shows 13C-13C coupling between C-6' (41.7 p.p.m.; 36 Hz) and the downfield 6'-methyl group (6'-Me) (24.3 p.p.m, 36 Hz). This 6'-Me, therefore, is derived from C-3' of mevalonate [Bennett, Norman & Maier (1981) Phytochemistry 20, 2343-2344]. An i.n.e.p.t. (insensitive nuclei enhanced by polarization transfer) pulse sequence demonstrated that the downfield 13C signal is produced by the 6'-Me that gives rise to the upfield 1H 6'-Me signal (23.1 d). The absolute configuration of this, the equatorial 6'-Me group, was determined as 6'-pro-R by decoupling and n.O.e. (nuclear-Overhauser-enhancement) experiments at 300 MHz using ABA, ABA in which the axial 6'-pro-S 5'-hydrogen atom had been exchanged with 2H in NaO2H and the 1',4'-cis- and 1',4'-trans-diols formed from these samples. The configuration at C-1' and at C-6' are now compatible with a chair-folded intermediate during cyclization, as proposed for beta- and epsilon-rings of carotenoids. ABA in solution exists, as in the crystalline form, with the ring in a pseudo-chair conformation. The side chain is axial and the C-3 Me and the C-5 hydrogen atoms are predominantly cis(Z).     

Isolation and characterization of variant clones of Chinese hamster cells after treatment with irradiated 5-iodouridine.

Variant clones were isolated from cultured Chinese hamster Don cells after treatment with irradiated 5-iodouridine. The following characters of a primary variant clone, C-11 and a secondary variant clone, C-24 were compared with those of the original clone C-1: colony-forming activity, growth rate in the presence of irradiated and unirradiated 5-iodouridine, distribution of chromosome numbers and cell cohesion. The variant clones C-11 and C-24 were partially resistant to unirradiated 5-iodouridine at lower concentration and C-24 cells were slightly resistant to short-term treatment with irradiated 5-iodouridine. Unlike clines C-1 and C-11 the variant clone C-24 showed no lag phase on growth in 5-iodouridine medium. The modal numbers of the chromosomes of all three clones were 22, like that of normal Chinese hamster diploid cells. Of the three clones, the variant C-24 cells showed the least mutual cohesion and the original C-1 cells showed the most. The possibility that an alteration in cellular membrane might be related to an increase in the resistance to radiosensitizing agents are discussed.     

Limonoids from fruit of Melia toosendan and their cytotoxic activity.

Two new limonoids, toosendanal and 12-O-methylvolkensin, were isolated from the fruits of Melia toosendan Sieb. et Zucc. along with three known limonoids, meliatoxin B1, trichillin H, and toosendanin. The structures of the new limonoids were established by spectroscopic methods, with toosendanal having C-1/C-29 and C-19/C-29 acetal bridges. Both meliatoxin B1 and toosendanin exhibit cytotoxic activity against KB cells.     

Purification and characterization of cytosolic aldolase from carrot storage root.

The time courses of incorporation of 13C from 13C-labelled glucose or acetate into cerebral amino acids (glutamate, glutamine and 4-aminobutyrate) and lactate were monitored by using 13C-n.m.r. spectroscopy. When [1-13C]glucose was used as precursor the C-2 of 4-aminobutyrate was more highly labelled than the analogous C-4 of glutamate, whereas no label was observed in glutamine. A similar pattern was observed with [2-13C]glucose: the C-1 of 4-aminobutyrate was more highly labelled than the analogous C-5 of glutamate. Again, no labelling of glutamine was detected. In contrast, [2-13C]acetate labelled the C-4 of glutamine and the C-2 of 4-aminobutyrate more highly than the C-4 of glutamate; [1-13C]acetate also labelled the C-1 and C-5 positions of glutamine more than the analogous positions of glutamate. These results are consistent with earlier patterns reported from the use of 14C-labelled precursors that led to the concept of compartmentation of neuronal and glial metabolism and now provide the possibility of distinguishing differential effects of metabolic perturbations on the two pools simultaneously. An unexpected observation was that citrate is more highly labelled from acetate than from glucose.     

Use of 13C-n.m.r. spectroscopy for the quantitative estimation of 3-O- and 3,6-di-O-substituted D-glucopyranosyl residues in alpha-D-glucans formed by the D-glucosyltransferases of Streptococcus sobrinus

The 13C-n.m.r. spectra of the three alpha-D-glucans from Streptococcus sobrinus and the dextran from Leuconostoc mesenteroides, which differ widely in the ratios of omega (terminal, nonreducing) D-glucopyranosyl groups: 3-:6-:3,6-linked D-glucopyranosyl (Glc) residues, were measured in 0.5M NaOH at 22 degrees. The C-1 signals of 3-O-substituted Glc in a linear sequence, 6-O-substituted Glc in a linear sequence, 3,6-di-O-substituted Glc in a (1----6)-linked sequence, and Glc attached to O-3 of 3,6-di-O-substituted Glc were distinguished from each other. The C-3 signal of 3,6-linked Glc appeared downfield by 0.6 to 1.0 p.p.m. compared to the C-3 signal of 3-linked Glc in a linear sequence. The C-6 signals of omega-terminal, 3-linked, 6-linked, and 3,6-linked Glc were also assigned. The C-2 signal of 3-linked Glc in a linear sequence appeared separately, at 73.76 p.p.m. Based on these assignments, the various D-glucopyranosyl residues of the S. sobrinus alpha-D-glucans were quantitatively estimated from the signal areas of the C-2 atom of 3-linked Glc, the C-3 atom of 3-linked and 3,6-linked Glc, the C-6 atom of 6-linked and 3,6-linked Glc, and the C-6 atom of the omega-Glc groups and 3-linked Glc residues. The figures thus derived for the linkage ratios were close to those obtained by methylation analysis.     

Bovine serum albumin. Study of the fatty acid and steroid binding sites using spin-labeled lipids.

Three spin-labeled derivatives of stearic acid and two derivatives of palmitic acid have been used to study the structure of the strong fatty acid binding site of bovine serum albumin. The steroid and indole binding sites have been studied using spin-labeled derivatives of androstol and indole, respectively. Paramagnetic resonance and fluorescence quenching data suggest that the fatty acid, steroid, and indole binding sites may be identical. The mobility of the nitroxyl group at C-8 of palmitic acid bound to albumin at a 1:1 molar ratio is unaffected when the carboxyl group is esterified. When the nitroxyl group is located at C-5 on this acid its motion is detectably increased by esterification of the carboxyl group but the magnitude of this change is small. This result suggests that the carboxyl group may play a minor role in the binding of fatty acids to the strongest fatty acid binding site of albumin. When stearic acid derivatives bearing the nitroxide at C-5, C-12, and C-16 are bound to albumin at a ligand to albumin ratio of 1, the order of mobility at 0-30 degrees is C-16 greater than C-12 congruent to C-5. Although motion at the methyl terminus is always greater than at the COOH terminus in the range 0-60 degrees, a simple monotonic increase in chain motion between the two termini is not observed. Arrhenius plots of the motion parameters for these bound fatty acids show two abrupt changes in slope. The temperature ranges for these changes are 15-23 degrees and 38-45 degrees. These results suggest that when one mole of spin-labeled fatty acid is bound to albumin, the protein undergoes a conformational change in each of these temperature ranges.     

The comparative specificity of 3 oestradiol-binding proteins. Rat alpha-foetoprotein, rat liver 17beta-hydroxy steroid dehydrogenase and anti-(oestradiol-6-carboxymethyloxime-bovine serum albumin) antiserum.

1. The specificity of 3 oestradiol-binding proteins was studied. Two of these proteins are naturally occurring (rat alpha-foetoprotein and rat liver microsomal 17beta-hydroxy steroid dehydrogenase) and the third is an artificially induced model, anti-(oestradiol-6-carboxymethyloxime-bovine serum albumin) gamma-globulins. 2. A specific binding procedure for each protein model permitted a determination of its affinity for oestradiol and for 30 other steroids. 3. The results obtained have brought to light the different areas of the steroid molecule that are important for its recognition by each of the three proteins. The two naturally occurring proteins (alpha-foetoprotein and 17beta-hydroxy steroid dehydrogenase) recognize the edge of the steroid defined by C-4, C-6, C-8 and C-15. On the other hand, the gamma-globulins recognize the opposite edge, i.e. that defined by C-2, C-10, C-11 and C-17. 4. Diethylstilboestrol, whose structure is analogous to that of a steroid, is only recognized by the two naturally occurring proteins.     

31P nuclear magnetic resonance-pH titrations of myo-inositol hexaphosphate.

With the use of 31P n.m.r. spectroscopy, the separate pKa values of each of the six phosphoric monoester groups of myo-inositol hexaphosphate were determined. The range of hydrogen-ion concentrations covered extended from that required for the phosphonium salts to that for the full dodecyl anion, and the determinations were carried out in the presence of sodium and tetrabutylammonium cations. The pKa for each phosphate grouping in the transition from the free acid forms of each group to the monoanion form of each group was determined to be: 1.1, C-2; 1.5, C-1 and C-3; 2.1, C-4 and C-6; and 1.7, C-5. In the mono- to di-anion transition, the pKa values were: 6.85, C-2; 7.60, C-5; 5.70 and 12.0, C-1 and C-3; and 10.0, C-4 and C-6. These data and the appearance of the 31P hexaphosphate n.m.r. multiplet are discussed in terms of conformations of myo-inositol hexaphosphate.     

Mechanisms of experimental cancer cachexia. Interaction between mononuclear phagocytes and colon-26 carcinoma and its relevance to IL-6-mediated cancer cachexia.

In a recent report we showed that IL-6 is an important mediator of experimental cancer cachexia in the colon-26 (C-26) tumor system. In culture, on a per cell basis, C-26.IVX cell line (which develops tumors and induces severe cachexia of syngeneic hosts) produces up to 60-fold less IL-6 than single cell suspensions prepared from freshly excised tumors. In this study, the mechanism behind this observation was investigated. Analysis of the cellular composition of progressing C-26 tumors indicated they contained up to 6% of macrophages. T cells, B cells, and granulocytes were not detected in the tumors. Because C-26.IVX line grown in vitro contained no macrophages, the possibility that macrophage products may augment IL-6 synthesis by the tumor cells was tested. Indeed, IL-1 beta in a dose-dependent manner and at picogram amounts could potentiate IL-6 production by the C-26 cell line. The presence of high affinity receptors for IL-1 on the C-26.IVX cell line was established. These cells expressed approximately 1500 IL-1 sites per cell with a dissociation constant of approximately 20 pM. Next, we attempted to mimic the situation in vivo by coculture of C-26.IVX cells with syngeneic peritoneal macrophages and found that this condition gives rise to an augmented IL-6 production similar to that observed with in vivo derived tumor cells or rIL-1 beta-treated C-26.IVX cells. Furthermore, anti-IL-1 type I receptor antibody completely blocked C-26.IVX IL-6 production induced by either rIL-1 beta or by peritoneal macrophages. Taken together, these data suggest a pathway of IL-6 production by C-26 tumors that involves a cellular interaction between IL-1R-expressing tumor cells and host-derived macrophages. The results also suggest that this interaction significantly contributes to cachectic events endured by the tumor-bearing host.     

Structural studies on sulfated oligosaccharides derived from the carbohydrate-protein linkage region of chondroitin 6-sulfate proteoglycans of shark cartilage. II. Seven compounds containing 2 or 3 sulfate residues.

Shark cartilage proteoglycans bear predominantly chondroitin 6-sulfate. After exhaustive protease digestion, reductive beta-elimination and subsequent chondroitinase ABC digestion, 13 hexasaccharide alditols were obtained from the carbohydrate-protein linkage region and six of them contain 0 or 1 sulfate and/or 1 phosphate residue (Sugahara, K., Ohi, Y., Harada, T., de Waard, P., and Vliegenthart, J. F. G. (1992) J. Biol. Chem. 267, 6027-6035). The other seven compounds, which represent approximately 60% of the isolated linkage hexasaccharides, were analyzed by chondroitinase ACII digestion in conjunction with high performance liquid chromatography and by 500-MHz one- and two dimensional 1H NMR spectroscopy. All seven compounds have the following conventional structure in common. [formula: see text] Two disulfated compounds have an O-sulfate on C-6 of the Gal-2 residue attached to xylitol in combination with an O-sulfate on C-4 or on C-6 of the GalNAc residue. The third disulfated compound has O-sulfate on C-6 of Gal-2, and also on C-6 of Gal-3. Two of the trisulfated compounds also have O-sulfate on C-6 of both Gal-2 and Gal-3 with in addition sulfate on C-6 or C-4 of GalNAc. The other two trisulfated compounds have O-sulfate on C-6 of Gal-2 and on C-4 of Gal-3 in conjunction with sulfate on C-6 or C-4 of GalNAc.     

Preparation and antigenic properties of androsterone-7-BSA conjugate.

The 7-carboxymethoximino derivative of androsterone (1) has been prepared from dehydroisoandrosterone-17-ethyleneketal by a sequence involving inversion at C-3, introduction of a carbonyl at C-7, and reduction of the double bond at C-5. The substance was condensed with BSA by the carbodiimide procedure to afford a conjugate which produced anti-androsterone antiserum in innoculated rabbits. The antiserum is sufficiently active to be useful in radioimmunoassay procedures.