ornithine cycle

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Related to ornithine cycle: citrulline, urea cycle

u·re·a cy·cle

the sequence of chemical reactions, occurring primarily in the liver, that results in the production of urea; the key reaction is the hydrolysis of l-arginine by arginase to l-ornithine and urea; l-ornithine is then converted to l-citrulline by a carbamoylation reaction, then to l-argininosuccinate by an amination reaction involving l-aspartic acid; finally, a lyase-dependent step generates arginine and fumarate.

ornithine cycle


an amino acid obtained from arginine by the action of the enzyme arginase which also splits off urea; it is an intermediate in urea biosynthesis.

ornithine carbamoyl transferase (OCT), ornithine transcarbamoylase
see ornithine carbamoyl transferase.
ornithine cycle
alternative name for urea cycle since ornithine is the carrier of the nitrogens.
ornithine decarboxylase test
a means of identifying different members of the Enterobacteriaceae as well as other gram-negative bacteria.
deficiency see gyrate atrophy.
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