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Biomedical subjects

R S Criddle

Publications and source records attributed to R S Criddle.

At least 73 records · Page 4Linked to original sources
PubMed1968

The kinetics of the reversible inhibition of heart lactate dehydrogenase through the formation of the enzyme-oxidized nicotinamide-adenine dinucleotide-pyruvate compounds.

The inhibition of lactate dehydrogenase at high pyruvate concentration was studied in three ways. First, a rapid decrease in the rate of the enzyme reaction was observed; secondly, the rate of formation of a pyruvate-NAD(+) compound was followed by the change in E(325); thirdly, the rate of quenching of the protein fluorescence was measured. The data obtained at pH6.0 at different temperatures and ionic strengths as functions of pyruvate, NAD(+) and enzyme concentrations show that the extent of inhibition can be correlated with the reversible formation of a compound between pyruvate and enzyme-bound NAD(+). It is suggested that the detailed kinetic analysis of the formation of this abortive ternary compound will give pertinent information about properties of the enzyme-NAD(+) compound involved in the normal catalytic process.

Chemical Phenomena↗
PubMed1967

Biogenesis of Mitochondria in Germinating Peanut Cotyledons II. Changes in Cytochromes and Mitochondrial DNA.

Biogenesis of mitochondria occurs in the germinating cotyledons of peanuts. This process was demonstrated by measuring both constitutive and enzymatic properties of mitochondria as a function of germination time. Direct counting by phase contrast microscopy of sucrose density gradient preparations showed that the number of mitochondria increased markedly during germination. DNA with a buoyant density distinct from the major cellular DNA was associated with these mitochondrial preparations. During germination the amount of this DNA in mitochondrial pellets increased. This increase closely paralleled the increase in number of mitochondria.Succinoxidase and succinic dehydrogenase increased during germination. Both activities were confined to the mitochondrial fraction. The rate of increase of succinoxidase activity was significantly greater than the rate of increase of succinic dehydrogenase and both increased at least initially at a greater rate than the amount of mitochondrial DNA or numbers of mitochondria.The amounts of cytochromes present in mitochondrial preparations were measured spectrophotometrically. All of the cytochromes increased in amount during germination. The rate of increase of cytochrome a - a(3) very close to the rate of increase in succinoxidase activity.

Journal Article↗