Purification of the second enzyme of chlorophyll biosynthesis from Chlamydomonas reinhardtii

Conference · Tue May 01 00:00:00 EDT 1990 · Plant Physiology, Supplement; (USA)

OSTI ID:5851307

Krishnasamy, S; Wang, Weiyeh ^[1]

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1. Univ. of Iowa, Iowa City (USA)

Delta-aminolevulinic acid (ALA) is the universal precursor for the synthesis of chlorophylls and tetrapyrroles. The first enzyme of the pathway activates glutamate by ligating it to its cognate tRNA. The second enzyme is a dehydrogenase which converts the activated glutamate on glu-tRNA to glutamate-1-semialdehyde (GSA). We now report the purification of the second enzyme, GSA dehydrogenase by using ammonium sulfate fractionation and column chromatography with DEAE Sepharose, Blue Sepharose and 2{prime},5{prime}-ADP Agrose. The native molecular weight of this enzyme, as determined by HPLC, was 130 KD. We have developed a specific assay for the dehydrogenase by measuring the formation of labeled GSA from ({sup 3}H)-glu-tRNA. The efficiency of glu-tRNA to GSA conversion by the dehydrogenase was low. However, this rate could be increased many fold by the addition of glu-tRNA synthetase, glutamate and ATP. We think under in vivo conditions, the first two enzymes of ALA biosynthesis may form a complex which operates much more efficiently.

• OSTI ID: 5851307
• Report Number(s): CONF-9007196-; CODEN: PPYSA
• Journal Information: Plant Physiology, Supplement; (USA), Vol. 93:1; Conference: Annual meeting of the American Society of Plant Physiologists, Indianapolis, IN (USA), 29 Jul - 2 Aug 1990; ISSN 0079-2241
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
OXIDOREDUCTASES
BIOSYNTHESIS
AMINOLEVULINIC ACID
CHLAMYDOMONAS
CHLOROPHYLL
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALGAE
AMINO ACIDS
CARBOXYLIC ACIDS
CHLOROPHYCOTA
ENZYMES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
PROTEINS
SYNTHESIS
UNICELLULAR ALGAE
550201* - Biochemistry- Tracer Techniques