scholarly journals The specificity of a 7 α-hydroxy steroid dehydrogenase from Escherichia coli

1976 ◽  
Vol 157 (1) ◽  
pp. 207-210 ◽  
Author(s):  
E S Haslewood ◽  
G A D Haslewood
Keyword(s):  
Escherichia Coli ◽  
Crude Enzyme ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Improved Method ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

1. Thirty-eight steroids were tested as substrates for a 7 alpha-hydroxy steroid dehydrogenase preparation from a strain of Escherichia coli; an improved method of making the crude enzyme is described. 2. Steroids having a 7 alpha-hydroxyl group in the molecule were substrates except (a) when the 5 beta-cholan-24-oic acid side chain was shortened to less than four carbon atoms and (b) in certain cases when sulphate ester groups were present in the molecule. 3. For testing with the enzyme, a new specimen of 7 alpha-hydroxy-3,12-dioxo-5 beta-cholan-24-oic acid was made, which had properties different from those previously described.

Molecular Mechanics Investigation on Side-Chain Conformations of a 17α-Ethyl-17β-hydroxy Steroid with Regard to Receptor Binding

1987 ◽  
Vol 42 (3) ◽  
pp. 221-224 ◽  
Author(s):  
Martin Bohl
Keyword(s):  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Molecular Mechanics ◽  
Receptor Protein ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Ring Conformation ◽  
Sterically Hinder ◽  
Chain Conformations ◽  
Hydroxy Steroid

Energetically favourable conformations for simultaneous intramolecular rotations of both the 17 α ethyl side chain and the 17 β hydroxyl group of a model steroid are calculated by MM2 molecular mechanics. In accordance with recent IR and NMR interpretations, the 17α substituent is found to preferably adopt conformations which may sterically hinder the formation of hydrogen bonds between the steroidal 17β oxygen atom and the receptor protein. Furthermore, the 17a ethyl substitution is computed to influence the D-ring conformation and to alter the location of the 17β oxygen function by 28 pm in space.

Cloning and expression of a Pseudomonas 3α-hydroxy steroid dehydrogenase-encoding gene in Escherichia coli

Gene ◽  
1993 ◽  
Vol 130 (1) ◽  
pp. 137-140 ◽  
Author(s):  
Koji Suzuki ◽  
Shigeru Ueda ◽  
Masanori Sugiyama ◽  
Shigeyuki Imamura
Keyword(s):  
Escherichia Coli ◽  
Cloning And Expression ◽  
Encoding Gene ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

scholarly journals Isolation and characterization of 17β-hydroxy steroid dehydrogenase from human erythrocytes

1972 ◽  
Vol 127 (4) ◽  
pp. 649-659 ◽  
Author(s):  
E. Mulder ◽  
G. J. M. Lamers-Stahlhofen ◽  
H. J. Van Der Molen
Keyword(s):  
Dehydrogenase Activity ◽  
Gel Filtration ◽  
Enzymic Activity ◽  
Hydroxyl Group ◽  
Unit Weight ◽  
Ph Optimum ◽  
Ammonium Sulphate Precipitation ◽  
Isolation And Characterization ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

1. The 17β-hydroxy steroid dehydrogenase was solubilized during haemolysis of erythrocytes and was isolated from the membrane-free haemolysate. Membrane preparations isolated in different ways did not contain 17β-hydroxy steroid dehydrogenase activity. The 17β-hydroxy steroid dehydrogenase activity in the haemolysate was concentrated by repeated ammonium sulphate precipitation and gel filtration on Sephadex G-150. The 17β-hydroxy steroid dehydrogenase activity of the purified preparation per unit weight of protein was 350–3000 times higher than the activity of the crude erythrocyte haemolysate. The 20α-hydroxy steroid dehydrogenase activity was lost during this purification procedure. 2. The 17β-hydroxy steroid dehydrogenase was NADP-dependent and had a pH optimum for conversion of testosterone between 8.5 and 10. For the molecular weight of the enzyme a value of 64000 was calculated from Sephadex chromatography results. 3. p-Chloromercuribenzoate inhibited the enzymic activity. The oxidative activity of the enzyme for the 17β-hydroxyl group was only partly inhibited when a large excess of 17-oxo steroids was added. The catalysing activity of the enzyme was influenced by the NADP+/NADPH ratio. The oxidation of the 17β-hydroxyl group in the presence of NADP+ proceeded faster than the reduction of the 17-oxo group with NADPH. When both reduced and oxidized cofactors were present the oxidation of the 17β-hydroxyl group was inhibited to a considerable extent. 4. The enzyme had a broad substrate specificity and not only catalysed the conversion of androstanes with a 17β-hydroxyl group, or 17-oxo group, but also the conversion oestradiol⇆oestrone. In addition the steroid conjugates dehydroepiandrosterone sulphate and oestrone sulphate were also converted. There were no indications that more than one 17β-hydroxy steroid dehydrogenase was present in the partially purified preparation.

A metabolic stability determination of Tetrahydrothiazolopyridine derivative a selective 11β-hydroxy steroid dehydrogenase type 1 (11β-hsd1) inhibitor

2017 ◽  
Vol 8 (3) ◽  
Author(s):  
MURUGESH KANDASAMY ◽  
MUHAMMED SALIHIN ◽  
MALLIKARJUNA RAO PICHIKA ◽  
SLAVKO KOMARNYTSKY ◽  
THIRUMURUGAN RATHINASABAPATHY
Keyword(s):  
Metabolic Stability ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

scholarly journals Binding Site of the Bridged Macrolides in the Escherichia coli Ribosome

2005 ◽  
Vol 49 (1) ◽  
pp. 281-288 ◽  
Author(s):  
Liqun Xiong ◽  
Yakov Korkhin ◽  
Alexander S. Mankin
Keyword(s):  
Escherichia Coli ◽  
Tight Binding ◽  
Dimethyl Sulfate ◽  
23S Rrna ◽  
Side Chain ◽  
Macrolide Antibiotics ◽  
Side Chains ◽  
Alkyl Aryl ◽  
E Coli ◽  
Exit Tunnel

ABSTRACT Ketolides represent the latest group of macrolide antibiotics. Tight binding of ketolides to the ribosome appears to correlate with the presence of an extended alkyl-aryl side chain. Recently developed 6,11-bridged bicyclic ketolides extend the spectrum of platforms used to generate new potent macrolides with extended alkyl-aryl side chains. The purpose of the present study was to characterize the site of binding and the action of bridged macrolides in the ribosomes of Escherichia coli. All the bridged macrolides investigated efficiently protected A2058 and A2059 in domain V of 23S rRNA from modification by dimethyl sulfate and U2609 from modification by carbodiimide. In addition, bridged macrolides that carry extended alkyl-aryl side chains protruding from the 6,11 bridge protected A752 in helix 35 of domain II of 23S rRNA from modification by dimethyl sulfate. Bridged macrolides efficiently displaced erythromycin from the ribosome in a competition binding assay. The A2058G mutation in 23S rRNA conferred resistance to the bridged macrolides. The U2609C mutation, which renders E. coli resistant to the previously studied ketolides telithromycin and cethromycin, barely affected cell susceptibility to the bridged macrolides used in this study. The results of the biochemical and genetic studies indicate that in the E. coli ribosome, bridged macrolides bind in the nascent peptide exit tunnel at the site previously described for other macrolide antibiotics. The presence of the side chain promotes the formation of specific interactions with the helix 35 of 23S rRNA.

DIFFICULTIES IN THE DIAGNOSIS OF THE ADRENOGENITAL SYNDROME IN INFANCY

PEDIATRICS ◽  
1972 ◽  
Vol 49 (2) ◽  
pp. 198-205
Author(s):  
C. H. Shackleton ◽  
F. L. Mitchell ◽  
J. W. Farquhar
Keyword(s):  
Hydroxylase Deficiency ◽  
Adrenogenital Syndrome ◽  
Steroid Excretion ◽  
21 Hydroxylase Deficiency ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

Pregnanetriol was not excreted by an infant (7 days old) who was later shown to have a defect in steroid 21-hydroxylase. However, the excretion of this compound increased during the following days (1.2 mg on the thirteenth day of life). A high excretion of 3β-hydroxy-Δ steroids was the most noticeable abnormality in steroid excretion noted on the seventh day of life (e.g., 3β, 16α-dihydroxy-5-pregnen-20-one, 15 mg; 3β, 21-dihydroxy-5-pregnen-20-one, 1.4 mg and 3β, 16α-dihydroxy-5-androsten-17-one, 7.4 mg). This high 3β-hydroxy-Δ steroid excretion results in difficulties in distinguishing a defect in 3β-hydroxy steroid dehydrogenase from a 21-hydroxylase deficiency. At the age of 14 months the principal steroids excreted were those predominant in other cases of 21-hydroxylase deficiency, viz. pregnanetriol and 5β-pregnane-3α, 17α, 20α-triol-11-one (11-oxo-pregnanetriol).

17α-HYDROXYLASE DEFICIENCY. A COMBINATION OF HYDROXYLATION DEFECT AND REVERSIBLE BLOCKADE IN ALDOSTERONE BIOSYNTHESIS

1979 ◽  
Vol 90 (3) ◽  
pp. 490-504 ◽  
Author(s):  
D. R. Rovner ◽  
J. W. Conn ◽  
E. L. Cohen ◽  
F. G. Berlinger ◽  
D. C. Kern ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Extracellular Fluid ◽  
Plasma Renin ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Hydroxylase Deficiency ◽  
Resultant Increase

ABSTRACT We have studied the hormonal secretion and excretion patterns in a patient with the XX type of 17α-hydroxylase deficiency. In the untreated state, the patient's urine contained only those steroids which do not require 17-hydroxylation in their biosynthesis. Aldosterone was not produced in the patient and the metabolic product of its immediate precursor, 18-hydroxy-11-dehydro-tetrahydrocorticosterone, was excreted in markedly elevated amounts. This apparent complete block in 18 oxidation was reversible upon long-term ACTH suppression within 27 days. Direct in vitro incubation of the patient's adrenal gland removed at operation demonstrated, 1) the complete lack of 17α-hydroxylase activity, 2) the functional block in the ability to oxidize the hydroxyl group at the 18 methyl side chain. The addition of physiological concentrations of angiotensin to the incubation medium further showed, 3) angiotensin mildly stimulated the entire aldosterone biosynthetic pathway, 4) angiotensin directly stimulated the conversion of 18-hydroxycorticosterone to aldosterone. We propose that in this patient, 17-hydroxylase deficiency produced a decreased plasma concentration of cortisol, followed by stimulation of deoxycorticosterone production by ACTH. The resultant increase in extracellular fluid volume suppressed plasma renin activity. This resulted in a low plasma concentration of angiotensin II which directly suppressed oxidation of 18-hydroxycorticosterone to aldosterone. This defect has been called corticosterone methyl oxidase defect type 2.

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