<prompt> The rate-limiting step in the biosynthesis of catecholamines is catalyzed byTyrosine hydroxylaseDopa decarboxylaseDopa mine f3 hydroxylaseCatechol-O-methyltransferase  <response>: The rate limiting step in the synthesis of catecholamines is catalysed by tyrosine hydroxylase Ref : guyton and hall textbook of medical physiology 12 edition page number:605,606,607 