Diamine oxidase ofLathyrus sativus seedlings. Purification and properties |
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Authors: | M R Suresh P R Adiga |
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Institution: | (1) Department of Biochemistry, Indian Institute of Science, 560 012 Bangalore;(2) Present address: Department of Biochemistry, Scripps Clinic and Research Foundation, La Jolla, California, USA |
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Abstract: | Diamine oxidase (EC 1.4.3.6) was purified from 5-day-old etiolated seedlings ofLathyrus sativus by MnCl2 treatment, (NH4)2SO4 and acetone fractionations, DEAE-Sephadex chromatography followed by gel filtration on Sephadex G-200. A single step purification
of the enzyme was achieved by using an immunoaffinity column, wherein rabbit antibodies to the homogeneous diamine oxidase
were coupled to CNBr-activated Sepharose. The enzyme thus obtained was homogeneous by electrophoretic, immunological and ultracentrifugal
criteria. It had anM
r of 148,000 (6.46S) and was a dimer with similar sub-units (M
r 75,000). Amino acid analysis showed the absence of cysteine residues although it contained five disulphide bonds. The enzyme
had copper (2.7 g atom/mol enzyme) but was not a glycoprotein. No absorption maximum in the visible region was detectable.
Ethylenediamine 1,3-diaminopropane and histamine were potent competitive inhibitors for the substrate putrescine. The addition
of monospecific antibodies to the enzyme increased the Km for benzyl amine without any change in the Vmax Diamine oxidase from pea seedling, partially purified, exhibited complete crossreactivity with the antibodies to theL. sativus enzyme. |
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Keywords: | Diamine oxidase Lathyrus sativus purification properties immunoaffinity procedure sub-units copper content |
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