D-enzymes

According to their genetic relationship and their biochemical mechanism of action (3-lactamases are divided into enzymes of the serine-protease type containing an active-site serine (molecular class A, C, and D enzymes) and those of the metallo-protease type (molecular class B enzymes), which contain a complex bound zinc ion. 

Class D enzymes (Mr of about 27,000) exhibit a high activity versus isoxazolyl penicillins, such as oxacillin and are referred to as the OXA-family. Surprisingly, the amino group of the SXXK lysine residues is carboxylated in the most active forms of the enzymes. Penicillins are generally better substrates than cephalosporins but mutations have been found which confer extended activity spectra to these enzymes. 

Thummel, K. E., Kunze, K. L., Shen, D. D., Enzyme catalysed processes of first-pass hepatic and intestinal drug extraction, Adv. Drug Del. Rev. 1997,... 

Another report describing an approach to achieve alleviation of sulfur repression came from the Matsui research group. The dsz genes were cloned into a strain Rhodococcus sp. strain T09 under the promoter rrn of the strain T09 using a Rhodococcus-E. coli shuttle vector [214,215], This resulted in a strain which desulfurized DBT to 2-HBP in presence of sulfate, cysteine, or methionine. Similar approach was also used by Kurane to construct a gene expressing dszA-D enzymes, which eliminate the sulfate inhibition effects [216],... 

A phospho-eryZ/iro-pentulokinase and a phosphoriboisomerase are found in spinach.184(d) Enzymes present in mammalian liver, in pigeon liver, and in bacteria catalyze the reaction of ATP with D-ribose 5-phosphate, giving... 

D. Enzyme-labeled antigen is used at a constant (and excess) concentration of approximately 10 pg/tnL (such that it is not the limiting factor in the assay), allowed to react, and excess is washed away (PBST). 

Munnecke, D. "Enzyme Hydrolysis of Organophosphate Insecticides, a Possible Disposal Method." J. App. Environ. Microbiol., Series 32, Issue 1, 7-13 (1976). Munnecke, D. and S. Bank. "Enzymatic Hydrolysis of Diazinon in Soil." Dept, of Bot. Micro., Univ. of Oklahoma, May 26, 1981. 

Three of the four classes of (3-lactamases, A, C, and D are serine nucleophile-based enzymes, while the fourth, class B, contains zinc metallo-(3-lactamases. Among the serine (3-lactamases, classes A and C are currently the most intensely studied. However, extended spectrum class D enzymes have, of late, been growing in clinical importance [309-314]. 

This book on Electrochemical (Bio)Sensor Analysis, edited by S. Alegret and A. Merko< i, is an additional step to advance the field of rapid analysis. It presents advanced sensor developments as well as practical applications of electrochemical (bio)sensors in various fields in a single source. The book contains 38 chapters grouped into seven sections (a) Potentiometric sensors, (b) Yoltammetric (bio)sensors, (c) Gas sensors, (d) Enzyme based sensors, (e) Affinity biosensors, (f) Thick and thin film biosensors, and (g) Novel trends. This interdisciplinary book has contributions from well-known specialists in the field and will be a useful resource for professionals with an interest in the application of electrochemical (bio)sensors. 

Gl. Galen, R. S., and Forman, D., Enzyme immunoassay of serum thyroxine with the AutoChemist multichannel analyzer. Clin. Chem. 23, 119—121 (1977). 

Some starch-deficient mutants of Arabidopsis and Chlamydomonas have been shown to be defective in a-l,4-glucanotransferase activity. The enzyme is also known as D-enzyme. The reaction it catalyzes is as follows ... 

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