Incubation o f deproteinized larval cuticle (chitin flakes) with purified arylphorin (calliphorin) or larval haemolymph o f Calliphora vicina resulted in the formation o f a chitin-protein complex. Enzymatic oxidation o f N-ß-alanyldopamine (N D A B ) in the presence o f chitin flakes or the chitin-protein complex, resulted in various degrees o f cross-linking o f N BA D quinone formed with chi...

Quinoprotein content and levels of external pyrroloquinoline quinone (PQQ) were determined for several bacteria under a variety of growth conditions. From these data and those from the literature, a number of factors can be indicated which are relevant for PQQ production. Synthesis of PQQ is only started if synthesis of a quinoprotein occurs, but quinoprotein synthesis does not depend on PQQ sy...

Conditions of oxidative stress may lead to cataract formation. Reaction of certain flavoproteins, the NADH: oxidoreductases, with different quinones is well known to form hydrogen-peroxide. This reaction was investigated to get more information on cataract induction by naphthalene and its quinone metabolites. Protein extracts from bovine lens cortex exhibit "diaphorase" activity, indicated as d...

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