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Reduced Pyridine Nucleotide Oxidases of Euglena gracilis var. bacillaris *
Author(s) -
MOHANTY MAHENDRA K.,
HUNTER FRISSELL R.,
MYERS JOSEPH B.
Publication year - 1977
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1977.tb00990.x
Subject(s) - diaphorase , euglena gracilis , reductase , biochemistry , enzyme , nadh dehydrogenase , nadph dehydrogenase , dehydrogenase , peroxidase , chemistry , nad+ kinase , biology , nitric oxide synthase , protein subunit , gene , chloroplast
SYNOPSIS. Cell‐free extracts of a streptomycin‐bleached strain of Euglena gracilis var. bacillaris have been examined for enzyme systems primarily responsible for the oxidation of reduced pyridine nucelotides. NADH lipoyl dehydrogenase, NADH and NADPH oxidase, NADH and NADPH diaphorase, and NADH and NADPH cytochrome c reductase have been demonstrated. The NADPH‐linked enzymes had lower activity rates and were less sensitive to N‐ethyl maleimide and p ‐hydroxymercuribenzoate than their NADH‐linked counterparts. NADH cytochrome c reductase was the most sensitive to antimycin A. Michaelis‐Menten constants ( K m ) determined were as follows: NADH diaphorase, 350 μ M; NADPH diaphorase, 200 μ M; NADH cytochrome c reductase, 13 μ M; NADPH cytochrome c reductase, 9 μ M; NADH oxidase, 100 μ M; NADPH oxidase 150 μ M; NADH lipoyl dehydrogenase, 0.35 μ M. Enzyme activities after storage at –5 C indicate that the diaphorases are less labile than the other tested enzymes, and the differential activities of the NADH and NADPH linked enzymes suggest that functionally they may have different roles.