English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

1. At 21 degrees C incubation of NADH-ubiquinone-1 reductase (Complex 1) with trypsin caused selective inhibition of nicotinamide nucleotide transhydrogenase activity. The reduction of K3Fe(CN)6 by NADH or NADPH was unaffected, but a slow decrease in the rate of reduction of ubiquinone-1 by NADH was observed. 2. The pH-dependence of nicotinamide nucleotide transhydrogenase activity differed in Complex I and trypsin-treated Complex I. The trypsin-labile activity had a pH optimum of approx. 6.5, whereas the trypsin-resistant activity had a pH optimum of approx. 5.5 or less. 3. The trypsinlabile transhydrogenase activity was specifically inhibited by butanedione or phenylglyoxal and was identified with the enzyme catalysing energy-linked transhydrogenase activity in submitochondrial particles. 4. Polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate revealed that trypsin caused degradation of a polypeptide of mol.wt 20500 in parallel with the loss of transhydrogenase activity. 5. At 30 degrees C and higher trypsin concentrations, the rate of reduction of K3Fe(CN)6 by NADH or NADPH slowly decreased. Increased lability of NADH-K3Fe(CN)6 reductase activity to trypsin was observed when the endogenous phospholipid of Complex I was depleted by detergent or phospholipase A treatment. 6. Polyacrylamide-gel electrophoresis indicated that removal of phospholipid allowed much more extensive degradation of constituent polypeptides by trypsin. The subunits of the low-molecular-weight (type II) dehydrogenase (53000 and 26000 mol.wt.) were, however, relatively resistant to trypsin even in phospholipid-depleted preparations.

biochemical journal. cellular aspects

The effects of proteolytic digestion by trypsin on the structure and catalytic properties of reduced nicotinamide-adenine dinucleotide dehydrogenase from bovine heart mitochondria