Properties of seleno-methionine substituted assimilatory nitrate reductase

Conference · Mon Mar 11 00:00:00 EST 1991 · FASEB Journal (Federation of American Societies for Experimental Biology); (United States)

OSTI ID:5373095

Solomonson, L P; Barber, M J ^[1]

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1. Univ. of South Florida, Tampa (United States)

Assimilatory NADH:nitrate reductase contains FAD, heme and Mo-pterin arranged in an NADH{yields}FAD{yields}heme{yields}Mo-Pterin{yields}NO{sub 3} electron transfer sequence. A functional Mo-pterin center is essential for all nitrate-reducing activities. To assess the possible functional role of Met, a Se-Met substituted NR was obtained by addition of Se-Met to ammonia-grown Chlorella cells prior to induction of NR activity. Increase in NADH:dehydrogenase partial activities and nitrate reductase protein proceeded normally following induction but little or no nitrate-reducing activity was expressed. This effect was observed with as little as 10{sup {minus}5} Se-Met and was prevented by a 10-fold excess of Met. A less pronounced effect was observed with 10{sup {minus}4}M Se-Cys. The purified Se-Met substituted enzyme exhibited the same apparent physical size, spectral properties and NADH dehydrogenase activities as control NR but was devoid of nitrate-reducing activities. These results suggest that one or more Met residues are essential for the catalytic function of the molybdo-pterin center of assimilatory NR.

• OSTI ID: 5373095
• Report Number(s): CONF-9104107-; CODEN: FAJOE
• Journal Information: FASEB Journal (Federation of American Societies for Experimental Biology); (United States), Vol. 5:4; Conference: 75. annual meeting of the Federation of American Societies for Experimental Biology (FASEB), Atlanta, GA (United States), 21-25 Apr 1991; ISSN 0892-6638
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
NITRATES
METABOLISM
OXIDOREDUCTASES
CHEMICAL PROPERTIES
CHLORELLA
ELECTRON TRANSFER
ENZYME ACTIVITY
METALLOPROTEINS
METHIONINE
ALGAE
AMINO ACIDS
CARBOXYLIC ACIDS
CHLOROPHYCOTA
DRUGS
ENZYMES
LIPOTROPIC FACTORS
MICROORGANISMS
NITROGEN COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PLANTS
PROTEINS
UNICELLULAR ALGAE
560300* - Chemicals Metabolism & Toxicology