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B6db references: 76023759

type Journal Article
authors Vijayalakshmi, K. R.; Rao, D. R.; Rao, M. R.
title Studies on a 2,3-diaminopropionate: ammonia-lyase from a Pseudomonad
journal Hoppe Seylers Z Physiol Chem
ui 76023759
year (1975)
volume 356
number 2
pages 193-201.
keywords Amino Acids, Diamino
abstract 2,3-Diaminopropionate:ammonia-lyase, an induced enzyme in a Pseudomonas isolate, has been purified 40-fold and found to be homogeneous by disc gel electrophoresis and by ultracentrifugation. Some of its properties have been studied. The optimum pH and temperature for activity are 8 and 40 degrees C, respectively. The enzyme shows a high degree of substrate specificity, acting only on 2,3-diaminopropionate; the D- isomer is only one-eighth as effective as the L-form. L-Homoserine and DL-cystathionine are not substrates, and 3-cyanolalanine does not inhibit its activity. It is a pyridoxal phosphate enzyme which requires free enzyme sulphhydryls for activity. The Km values for L-2,3- diaminopropionate and pyridoxal phosphate are 1mM and 25 muM, respectively. The molecular weight of the enzyme is about 80 000 as determined by gel filtration. On treatment with 0.5M urea or guanidine by hydrochloride, the enzyme dissociates into inactive subunits with an approximate molecular weight of 45 000. One mole of the active enzyme binds one mole of pyridoxal phosphate. The bacterial enzyme seems to be quite different in many of its properties from the rat liver enzyme which also exhibits the substrate specificity of cystathionine gamma- lyase.
last changed 2002/11/12 16:17

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