Steric factors involved in the action of glycosidases and galactose oxidase

α-(1→2)-$\text{L}\text{=}$-Fucosidase, β-$\text{D}\text{=}$-galactosidase and galactose oxidase are sterically hindered by certain types of branching in the oligosaccharide chains. 1) β-$\text{D}\text{=}$-Galactosidase will not cleave galactose when the penultimate sugar carries a sialic acid residue as in I. 2) Galactose Oxidase will not oxidize the galactose residue in trisaccharide I but will in II. Moreover, neither galactose nor $\text{N}$-acetylgalactosamine, glycosidically bound as in III, is susceptible to oxidation with galactose oxidase until the α-(1→2) linkage between them is cleaved by $\text{α-}\text{N}\text{-acetylgalactosaminidase}$. 3) α-(1→2)-$\text{L}\text{=}$-Fucosidase action is inhibited by $\text{α-(1→3)-}\text{N}\text{-acetylgalactosaminyl}$ or galactosyl residue, as in III and IV. Removal of the terminal sugars makes the fucosyl residue susceptible to fucosidase action.

     

Structural studies on the extracellular polysaccharide of the red alga, Porphyridium cruentum

Partial acid hydrolyzates of the extracellular polysaccharide from Porphyridiunm cruentum yield three disaccharides and two uronic acids. These constitute all of the uronic acid in the polymer. The novel disaccharides are 3-O-(α-$\text{D}$-glucopyranosyl- uronic acid)-$\text{L}$-galactose, 3-O-(2-O-methyl-ca-glucopyranosyluronic acid)-$\text{D}$- galactose, and 3-0-(2-0-methyl-a-$\text{D}$-glucopyranosyluronic acid)-$\text{D}$-glucose. The polyanion of high molecular weight contains $\text{D}$- and $\text{L}$-galactose, xylose, $\text{D}$-glucose, $\text{D}$-glucuronic acid and 2-O-methyl-D-glucuronic acid, and sulfate in molar ratio (relative to $\text{D}$-glucose) of 2.12:2.42:1.00:1.22:2.61. Preliminary periodate-oxidation studies suggest that the hexose and uronic acids are joined to other residues by ( 1→3) glycosidic linkages. About one-half of the xylose residues are (1→3)-linked.     

The synthesis of methyl 4-O-(4-O-α-d-galactopyranosyl-β-d-galactopyranosyl)-β-d-glucopyranoside: The methyl β-glycoside of the trisaccharide related to Fabry's disease

As part of a program to synthesize the ceramide trisaccharide (1) related to Fabry's disease, methyl 4-O-(4-O-α-$\text{d}$-galactopyranosyl-β-$\text{d}$-galactopyranosyl)-β-$\text{d}$-glucopyranoside (12) was prepared. Methyl β-lactoside (2) was converted into methyl 4-O-(4,6-O-benzylidene-β-$\text{d}$-galactopyranosyl)-β-$\text{d}$-glucopyranoside (4). Methyl 2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-β-$\text{d}$-galactopyranosyl)-β-$\text{d}$-glucopyranoside (7) was synthesized from 4 through the intermediates methyl 2,3,6-tri-O-benzoyl-4-O-(4,6-O-benzylidene-2,3-di-O-benzoyl-β-$\text{d}$-galactopyranosyl)-β-$\text{d}$-glucopyranoside (5) and methyl 2,3,6-tri-O-benzoyl-4-O-(2,3-di-O-benzoyl-β-$\text{d}$-galactopyranosyl)-β-$\text{d}$-glucopyranoside (6). The halide-catalyzed condensation of 7 with 2,3,4,6-tetra-O-benzyl-$\text{d}$-galactopyranosyl bromide (8) gave methyl 2,3,6-tri-O-benzoyl-4-O-[2,3,6-tri-O-benzoyl-4-O-(2,3,4,6-tetra-O-benzyl-α-$\text{d}$-galactopyranosyl)- β-$\text{d}$-galactopyranosyl]-β-$\text{d}$-glucopyranoside (10). Stepwise deprotection of 10 led to 12, the methyl β-glycoside of the trisaccharide related to Fabry's disease.     

11-Trans leukotriene C: A naturally occurring slow reacting substance

A slow reacting substance, produced by murine mastocytoma cells, has been shown to have the structure 5(S)-hydroxy-6(R)-$\text{S}$-glutathionyl-7,9,11-$\text{trans}\text{-14-}\text{cis}\text{-eicosatetraenoic acid (11-}\text{trans}$ leukotriene C, previously referred to as leukotriene C-2) by ultraviolet spectroscopy, amino acid analyses, lipoxygenase conversion and comparisions with a synthetic compound of known structure and stereochemistry.     

Leukotriene A: stereochemistry and enzymatic conversion to leukotriene B

Leukotriene A was assigned the structure 5(S)-$\text{trans}$-5,6-oxido-7,9-$\text{trans}\text{-11,14-}\text{cis}$-eicosatetraenoic acid by the enzymatic conversion of a synthetic product of known stereochemistry into the naturally occurring isomer of 5(S),12(R)-dihydroxy-6,8,10,14-eicosatetraenoic acid in human polymorphonuclear leukocytes.     

The synthesis,characterization, and preliminary biological evaluation of 1-β-D-arabinofuranosylcytosine-5′-diphosphate-L-1,2-dipalmitin

Recently, 1-β-$\text{D}$-arabinofuranosylcytosine-5′-diphosphate-$\text{DL}$-1,2-dipalmitin (VIa) was reported to inhibit the growth of L51784 cells in mice and of human colon carcinoma HCT-15 cells, also in mice. This paper describes the synthesis of a single diastereomer by conversion of 1-β-$\text{D}$-arabinofuranosylcytosine 5′-monophosphate (II) to the nucleoside 5′-phosphomorpholidate (III), followed by reaction with $\text{L}$-α-dipalmitoylphosphatidic acid (IV) to give 1-β-$\text{D}$-arabinofuranosylcytosine-5′-diphosphate-$\text{L}$-1,2-dipalmitin (V) in good yield. The separation of the product is described and its characterization by chromatography, elemental analysis, and spectroscopic methods. The lipophilic nature of V renders it insoluble in aqueous media and a method of sample preparation utilizing sonication techniques is described which provides a clear solution suitable for biological evaluation. In addition, the ability of V to inhibit the $\text{in}\text{vitro}$ growth of L1210 cells and of mouse myeloma MPC 11 cells is desscribed and compared with 1-β-$\text{D}$-arabinofuranosylcytosine (I) and other lipophilic prodrugs of I.     

The nature of mannose-containing material which accumulates in cultured fibroblasts from patients with mannosidosis

Fibroblasts from a patient with mannosidosis were grown in a medium containing a radioactive monosaccharide (D[U-¹⁴C]mannose or $\text{N-}\text{acetyl}\text{-}\text{D}\text{-[1-14}\text{C}\text{]-}\text{glucosamine}$). An accumulation of radioactive material was observed. It was possible to prevent the accumulation to a certain degree by the addition of human liver α-D-mannosidase to the fibroblast medium. After six days of fibroblast culture the majority of the accumulated material had a molecular weight in the oligosaccharide range and was stationary during high-voltage electropresis. Paper chromatography of the stationary material separated three radioactive compounds with the same chromatographic mobilities as the oligosaccharides $\text{α-}\text{D}\text{-}\text{Man}\text{-(1 → 3)-β-}\text{D}\text{-}\text{Man}\text{-(1 → 4)-}\text{D}\text{-}\text{GlcNAc}\text{(I), α-}\text{D}\text{-}\text{Man}\text{-(1 → 2)- α-}\text{D}\text{-}\text{Man}\text{-(1 → 3)-β-}\text{D}\text{-}\text{Man}\text{-(1 → 4)-}\text{GlcNAc}$ (II), and $\text{α-}\text{D}\text{-}\text{Man}\text{-(1 → 2)-α-}\text{D}\text{-}\text{Man}\text{- (1 → 2)-α-}\text{D}\text{-}\text{Man}\text{-(1 → 3)-β-}\text{D}\text{-}\text{Man}\text{-(1 → 4)-}\text{GlcNAc}$ (III) previously isolated from the urine of patients with mannosidosis. Degradation of the three radioactive compounds with jack bean α-mannosidase gave D-mannose and a disaccharide (containing D-mannose and $\text{N-}\text{acetyl}\text{-}\text{D}\text{-}\text{glucosamine}$). Thus the three main compounds observed in the fibroblast from patients with mannosidosis are most probably identical to the oligosaccharides I–III.     

Side-specific analogues for the rat adipocyte sugar transport system

(1) 4,6-O-Ethylidene-d-glucose is a good inhibitor of adipocyte sugar transport from the external surface. Using radioactively labelled 4,6-O-methylidene-d-glucose we have shown that this compound is not taken up into cells by the hexose transporter but through a route which is insulin insensitive, d-glucose insensitive, temperature sensitive and which is slightly inhibited by phloretin. When efflux of 3-O-methyl-d-glucose is studied with 4,6-O-methylidene-d-glucose only present inside the cells then no detectable inhibition is observed indicating that this compound is a good side-specific analogue with a high affinity for only the external site of the hexose transporter. (2) Radioactively labelled alkyl-β-d-glucosides have been prepared. These also penetrate the adipocyte membrane by an insulin and d-glucose insensitive route. The half-times for equilibration with methyl-, n-propyl-, and $\text{n-}\text{butyl}\text{-β-}\text{d}\text{-}\text{glucosides}$ are 255, 9.45 and 3.3 min, respectively, indicating that the uptake rates are dependent upon the size of the alkyl group. (3) The glucosides show poor inhibition of 3-O-methyl-d-glucose transport when added to the external solution only. When cells are preincubated with $\text{n-}\text{propyl}\text{-β-}\text{d}\text{-}\text{glucoside}$ and $\text{n-}\text{butyl}\text{-β-}\text{d}\text{-}\text{glucoside}$ an increase in the amount of inhibition of 3-O-methyl-d-glucosez uptake is observed. This increase in inhibition correlates well with the glucoside uptake rates and indicates that availability of the glucosides at the internal surface of the transporter is required for inhibition. This has been confirmed by measuring 3-O-methyl-d-glucose exit in the presence of $\text{n-}\text{propyl}\text{-β-}\text{d}\text{-}\text{glucoside}$ at the internal surface only. Thus, $\text{n-}\text{propyl}\text{-β-}\text{d}\text{-}\text{glucoside}$ is a good side-specific analogue with high affinity only for the internal site of the hexose transporter. (4) $\text{n-}\text{Propyl}\text{-β-}\text{d}\text{-}\text{glucoside}$ inhibition of d-allose transport is fully reversible. If cells are washed after a preincubation with the analogue then the inhibition is lost. The $\text{n-}\text{propyl}\text{-β-}\text{d}\text{-}\text{glucoside}$ inhibition of d-allose transport is reduced competitively by 3-O-methyl-d-glucose. (5) 6-O-Propyl-d-galactose has low affinity for both internal and external sites.     

Deamination of 2-amino-2-deoxyhexitols and of their per-O-methylated derivatives with nitrous acid

The products of nitrous acid deamination of per-O-methylated 2-amino-2-deoxy-d-glucitol and $\text{2-}\text{amino}\text{-2-}\text{deoxy}\text{-3-O-β-}\text{d}\text{-galactopyranosyl-}\text{d}\text{-glucitol}$ and its per-O-methylated derivative have been characterized by g.l.c.—mass spectrometry after treatment with sodium borodeuteride and further substitution by acetylation, methylation, or (trideuteriomethyl)ation. The results confirm that the most important reaction pathway (1) involves a 1 → 2-hydride shift to give $\text{2-}\text{deoxy-}\text{d}\text{-arabino-}\text{hexoses}$, but that significant side-reactions include (2) solvolytic displacement at C-2, (3) a 3 → 2-hydride shift, to give $\text{2-}\text{deoxy-}\text{d}\text{-erythro-3-}\text{hexuloses}$, and (4) a C-4→C-2 migration to give $\text{2-}\text{deoxy}\text{-2-C-}\text{(hydroxymethyl)-}\text{d}\text{-ribose}$ and -d-arabinose. Reactions (3) and (4) result in elimination of the original 3-O-substituents, with the exposure of new reducing groups, from oligosaccharides terminated by 3-O-substituted 2-amino-2-deoxyhexitols.     

Polyamine metabolism in the kidneys of castrated and testosterone-treated mice after administration of methylglyoxal bis(guanylhydrazone)

The effects of methylglyoxal bis(guanylhydrazone) on $\text{S-}\text{adenosyl}\text{-}\text{l}\text{-}\text{methionine}$ decarboxylase (EC 4.1.1.50) activity were studied in the mouse kidney stimulated to growth by testosterone administration. The drug was found to be a potent inhibitor of the enzyme in vitro. Administration of methylglyoxal bis(guanylhydrazone) in vivo resulted in a transient inhibition followed by a strong enhancement of the enzyme activity. Dialysis of the kidney extract, to remove remaining methylglyoxal bis(guanylhydrazone), revealed a great and rapid increase in the activity of $\text{S-}\text{adenosyl}\text{-}\text{l}\text{-}\text{methionine}$ decarboxylase. Injections of testosterone to castrated mice resulted in a marked increase in kidney weight and an accumulation of renal putrescine, spermidine and spermine. These effects of testosterone could not be blocked by simultaneous injections of methylglyoxal bis(guanylhydrazone). It appears that due to secondary effects by which the inhibition of methylglyoxal bis(guanylhydrazone) on $\text{S-}\text{adenosyl}\text{-}\text{l}\text{-}\text{methionine}$ decarboxylase activity is circumvented the inhibitor seems to be of uncertain value in attempts to decrease selectively the in vivo levels of polyamines.     

Fluorescent probe studies of mixed micelles of phospholipids and bile salts. Effect of cholesterol incorporation

The binding of the fluorescent alkylamines, $\text{N-(2-}\text{aminoethyl}\text{)-5-}\text{dimethylamino-1-naphthalene}$ sulfonamide, $\text{N-(5-}\text{aminopentyl}\text{)-5-}\text{dimethylamino-1-naphthalene}$ sulfonamide (dansyl cadaverine) and $\text{N-(10-}\text{aminodecyl}\text{)-5-}\text{dimethylamino-1-napthalene}$ sulfonamide with phospholipid and phospholipid-deoxycholate micelles, has been shown to increase with the length of the alkyl spacer chain. The probes bind more effectively to micelles containing unsaturated phospholipids and do not interact strongly with bile salt solutions at low concentrations. Cholesterol incorporation into mixed micelles results in a quenching of probe fluorescence due to displacement of probe molecules. The enhanced rigidity of the mixed micelles on solubilizing cholesterol is established by a decrease in pyrene excimer fluorescence and by the less effective perturbation of the micellar structure by 1-anilino-8-naphthalene sulfonate. The anionic probe 1-anilino-8-naphthalene sulfonate is also displaced from the mixed micelles when cholesterol is incorporated, suggesting a dominant role for packing and hydrophobic effects in binding both positively and negatively charged probes.     

Biosynthesis of tylosin: Oxidations of 5-O-mycaminosylprtylonolide at C-20 and C-23 with a cell-free extract from Streptomycesfradiae

The enzymatic conversion of various tylosin precursors was carried out using a cell-free system of the tylosin producer $\text{Streptomyces}\text{fradiae}$ to determine the order and intermediates of oxidations of the 16-membered branched lactone ring at C-20 and C-23 in the biosynthesis of tylosin. It was found that the order of the oxidation of the lactone is: (1) hydroxylation of 5-$\text{O}$-mycaminosylprotylonolide at C-20, (2) oxidation of C-20 hydroxymethyl to formyl, (3) hydroxylation at C-23 to give 5-$\text{O}$-mycaminosyltylonolide. The formation of 23-hydroxy-5-$\text{O}$-mycaminosylprotylonolide from 5-$\text{O}$-mycaminosylprotylonolide was not observed.     

Evidence for 5,12-dihydroxy-6,8,10,14-eicosatetraenoate as a mediator of human neutrophil aggregation

The human polymorphonuclear neutrophil (PMN) aggregation responses to 5(S),12(R)-dihydroxy-$\text{cis}$-6,14-$\text{trans}$-8,10-eicosatetraenoate (diHETE), C5a, N-formyl-methionyl-leucyl-phenylalanine (FMLP), and 1-$\text{0}$-alkyl-2-$\text{0}$-acetyl-$\text{sn}$-glycero-3-phosphocholine (AAGPC) were desensitized by preincubating the cells with small amounts of diHETE. Desensitization developed rapidly, persisted in washed cells, and was not due to stimulus inactivation. The desensitized cells exhibited normal aggregation responses to ionophore A23187 and phorbol myristate acetate (PMA). Thus, responsiveness to diHETE appears necessary for the aggregation response to C5a, FMLP, and AAGPC. Endogenous diHETE, which forms rapidly in cells challenged with these latter stimuli, may mediate their aggregating actions.     

Influence of the tubular flow rates on the endocytic uptake and the excretion of horseradish peroxidase by rat kidney

A third major chemical constituent of slow reacting substance (SRS-A) has been shown to possess the chemical structure 5(S)-hydroxy-6(R)$\text{S}$-cysteinyl-7,9-$\text{trans}$-11,14-$\text{cis}$-eicosatetraenoic acid (leukotriene E). Comparison of the biological activities of leukotriene E and the 11-$\text{trans}$ stereoisomer on guinea pig airways, ileum, and cutaneous microvasculature has revealed a noteworthy dependence of activity on stereochemistry with leukotriene E being much more potent in each system.     

Behavioral comparisons of the stereoisomers of tetrahydrocannabinols

The potencies of (?)-$\text{trans}$-Δ⁹-THC, (+)-$\text{trans}$-Δ⁹-THC, (+)-$\text{cis}$-Δ⁹-THC, (?)-$\text{trans}$-Δ⁸-THC and (+)-$\text{trans}$-Δ⁸-THC were compared in several different species. (?)-$\text{trans}$-Δ⁹-THC was 100 times more potent than (+)-$\text{trans}$-Δ⁹-THC in depressing schedule-controlled responding in monkeys. The (+)-$\text{trans}$ isomers were less effective than their corresponding (?)-$\text{trans}$ isomers in the dog static-ataxia test, but potency ratios could not be determined due to a lack of dose-responsiveness of the (+)-$\text{trans}$ isomers. However, it appeared that their potency differed by at least ten fold. The potency of (+)-$\text{cis}$-Δ⁹-THC in the dog static-ataxia test was comparable to that of (+)-$\text{trans}$-Δ⁹-THC. The hypothermia in mice produced by the (?) isomers of $\text{trans}$-Δ⁹-THC and $\text{trans}$-Δ⁸-THC were 9.1 and 30.4 times greater than that produced by their respective (+)-isomers. Also, the potency ratio of the (+)- and (?)-$\text{trans}$-Δ⁹-THC was 5.6 as measured by depression of spontaneous activity in mice. The magnitude of the potency ratios of the THC stereo-isomers is dependent upon the species and the pharmacological test used.     

The role of the sites for ATP of the Ca2+-ATPase from human red cell membranes during Ca2+-phosphatase activity

1. In the presence of ATP, the Ca²⁺ pump of human red cell membranes catalyzes the hydrolysis of $\text{p-}\text{nitrophenyl}$ phosphate. The requirement for ATP of the Ca²⁺-$\text{p-}\text{nitrophenylphosphatase}$ activity was studied in relation to the two classes of site for ATP that are apparent during Ca²⁺ -ATPase activity. 2. (a) The $\text{K}{}_{0.5}$ for ATP as activator of the Ca²⁺ -$\text{p-}\text{nitrophenylphosphatase}$ extrapolated at 0 mM PNPP is equal to the $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ of the Ca²⁺ -ATPase. (b) PNPP competes with ATP and its effectiveness is the same regardless the nucleotide acts as the substrate of the Ca²⁺ -ATPase or as activator of the Ca²⁺ -$\text{p-}\text{nitrophenylphosphatase}$. 3. PNPP at the high-affinity site does not substitute for ATP as activator of the Ca²⁺ -$\text{p-}\text{nitrophenylphosphatase}$. 4. At ATP concentrations that almost saturate the high-affinity site, Ca²⁺ -$\text{p-}\text{nitrophenylphosphatase}$ activity increases as a function of PNPP along an S-shaped curve, while Ca²⁺ -ATPase activity is partially inhibited along a curve of the same shape and apparent affinity. The fraction of Ca²⁺ -ATPase activity which is inhibited by PNPP is that which results from occupation of the low-affinity site by ATP. 5. Activation of the Ca²⁺ -ATPase by ATP at the low-affinity site is associated with inhibition of the Ca²⁺ -$\text{p-}\text{nitrophenylphosphatase}$ activity. Both phenomena take place with the same apparent affinity and along curves of the same shape. 6. Experimental results suggest that: (a) the Ca²⁺ -$\text{p-}\text{nitrophenylphosphatase}$ activity depends on ATP at the high-affinity site; (b) PNPP is hydrolyzed at the low-affinity site; (c) Ca²⁺ -ATPase activity at the high-affinity size persists during Ca²⁺ -$\text{p-}\text{nitrophenylphosphatase}$ activity.     

Stereospecific synthesis of a novel series of pyridine nucleosides

Condensation of $\text{3,5-}\text{di}\text{-O-}\text{benzoyl}\text{-β-}\text{d}\text{-}\text{ribofuranosyl}$ chloride severally with 3-acetyl-5-alkylpyridines, 5-alkyl-3-methoxycarbonylpyridines (alkyl = Me, Et, Pr, and ⁱPr), 5-isopropylnicotinamide, and 3,5-diacetylpyridine bis(ethylene acetal) in acetonitrile at ?5° gave the corresponding $\text{1-(3,5-}\text{di}\text{-O-}\text{benzoyl}\text{-β-}\text{d}\text{-}\text{ribofuranosyl}\text{))-3,5-}\text{disubstituted}$ pyridinium chlorides in excellent yield (90%). From the reaction of a series of $\text{2,3-O-}\text{isopropylidene}\text{-β-}\text{d}\text{-ribofuranosyl}$ halides with 3-acetyl-5-methyl-pyridine at room temperature, the α-nucleosides were obtained.     

Characterization and application of a radioimmunoassay for beta-endorphin using an antiserum with negligible cross-reactivity against beta-lipotropin

High avidity antisera against β-endorphin $\text{(β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}\text{)}$ were obtained in two of five rabbits immunized with unconjugated synthetic human $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$. One of these antisera (K-7762) cross-reacted 1.5% on a molar basis with β-lipotropin $\text{(β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{LPH}\text{)}$ and did not recognize leucine-enkephalin in a concentration as high as 0.2 mmol/l. The cross-reaction with methionine-enkephalin $\text{(β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{LPH}\text{61–65)}$ was 9%, while that with α-endorphin ($\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{LPH}$ 61–76) was 69%. This implied that the specific recognition site was in the amino-terminal region of $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$. Although this sequence is present in $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{LPH}$ it was poorly recognized by the antiserum, suggesting that the free amino-terminal is essential. This interpretation was supported by the finding that $\text{α-N-}\text{acetyl}\text{-β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$ was equally poorly recognized by the antiserum. The sensitivity of the radioimmunoassay was 1.9 pmol/l. $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$ was not detectable (< 3 pmol/l) in 26 of 27 extracted plasma samples in healthy blood donors, in one it was 5 pmol/l. In five of six patients with an enlarged sella turcica, but without clinical and laboratory evidence of pituitary dysfunction, $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$ was detectable ($\text{5 ± 3}\text{pmol/l}$; mean ± S.D.) after metyrapone. $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$ was elevated in Addison's disease (23, 54 and 76 pmol/l), Nelson's syndrome (37, 39 and 109 pmol/l), ectopic ACTH production (27, 59 and 76 pmol/l), but only detectable in one of three samples from patients with Cushing's disease (7 pmol/l). Gel chromatography of extracts of porcine pituitary revealed only one immunoreactive peak co-eluting with synthetic human $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$. The specificity of the antiserum K-7762 was such that the $\text{β}{}_{\mathrm{<mtext>h</mtext>}}\text{-}\text{EP}$ concentration in plasma extracts could be reliably estimated by radioimmunoassay without prior chromatography.     

Studies in antifertility agents — Part XLI: Secosteroids — X: Syntheses of various stereoisomers of (±) 2,6β-diethyl-7α-ethynyl-3-(p-hydroxyphenyl)-trans-bicyclo[4.3.0]nonan-7β-ol

The syntheses of (±) 2α,6β-diethyl-7α-ethynyl-3α-($\text{p}$-hydroxyphenyl)-$\text{trans}$-bicyclo[4.3.0]nonan-7β-ol ($\text{8}$), (±)2β,6β-diethyl-7α-ethynyl-3β-($\text{p}$-methoxyphenyl)-$\text{trans}$-bicyclo[4.3.0]nonan-7β-ol ($\text{12}$) and (±) 2α,6β-diethyl-7α-ethynyl-3β-($\text{p}$-hydroxyphenyl)-$\text{trans}$-bicyclo[4.3.0]nonan-7β-ol ($\text{18}$) and their derivatives, which are essentially B-seco-steroids having $\text{cis-anti-trans}\text{,}\text{cis-syn-trans}$ and $\text{trans-anti-trans}$ geometries have been carried out. A study of their antiimplantation activities (AI) and receptor binding affinities (RBA) show that $\text{trans-anti-trans}$ compounds are biologically most potent, followed by the corresponding $\text{cis-anti-trans}$ and $\text{cis-syn-trans}$ compounds. The most potent compound $\text{18}$ is active at 1 mg/kg in rats. Introduction of 7α-ethynyl group increases their AI activity; however, no significant effect on their RBA is observed.     

Theoretical studies on the modes of binding of some of the derivatives of d-mannose to concanavalin A

The possible modes of binding for $\text{methyl}\text{-α-}\text{d}\text{-mannopyranoside}$, $\text{methyl}\text{-β-}\text{d}\text{-mannopyranoside}$, $\text{2-O-}\text{methyl}\text{-α-}\text{d}\text{-mannopyranoside}$, $\text{methyl-2-O-methyl}\text{-α-}\text{d}\text{-mannopyranoside}$ and $\text{methyl}\text{-α-}\text{d}\text{-N-}\text{acetylmannosamine}$ to concanavalin A have been investigated using theoretical methods. All these sugars, except $\text{methyl}\text{-α-}\text{d}\text{-N-}\text{acetylmannosamine}$, reach the active site of concanavalin A with a highly restricted number of binding orientations. Present investigations suggest that the failure of $\text{methyl}\text{-α-}\text{d}\text{-N-}\text{acetylmannosamine}$ to bind to concanavalin A is not so much due to steric factors as to repulsive electrostatic interactions. $\text{Methyl}\text{-2-O-}\text{methyl}\text{-α-}\text{d}\text{-mannopyranoside}$ can bind to concanavalin A in one mode whereas the other sugars can bind in more than one mode. The high potency of $\text{methyl}\text{-α-}\text{d}\text{-mannopyranoside}$ over $\text{methyl}\text{-β-}\text{d}\text{-mannopyranoside}$ is mainly due to the possibility of hydrophobic interactions of the α-methoxy group with Leu(99) or Tyr(100) and also due to the possibility of formation of better and more hydrogen bonds with the protein. A comparison of these data with those for the d-glucopyranosides suggests that the change of the hydroxyl at the C-2 atom from equatorial to axial orientation increases the stereochemically allowed region as well as the possible binding modes. From these studies it is also suggested that the overall shape of the oligosaccharides rather than the terminal or internal mannose alone affects the binding potency of saccharides to concanavalin A.