BIOCHEMISTRY: New Activity, Old Enzyme

'New uses for an Old Enzyme'--the Old Yellow Enzyme family of flavoenzymes.

As the first flavin-dependent enzyme identified, and by virtue of its simplicity, the yeast Old Yellow Enzyme (OYE) has been characterized in detail by the whole gamut of physical techniques. Despite this scrutiny, the true physiological role of the enzyme remains a mystery. After 60 years in isolation, OYE has become the archetype of a growing family of flavoenzymes that have been discovered t...

Phosphorylase phosphatase: new horizons for an old enzyme.

Protein phosphatase-1, originally studied as phosphorylase phosphatase, is one of the major ser/thr protein phosphatases. It has a long history and a complex enzymology. It consists of a catalytic subunit of 37 kDa, which is bound to a number of different regulatory or targeting subunits. These are believed to restrict its activity to its immediate microenvironment and thus define its specifici...

Phytase, a new life for an "old" enzyme.

Phytases are phosphohydrolytic enzymes that initiate stepwise removal of phosphate from phytate. Simple-stomached species such as swine, poultry, and fish require extrinsic phytase to digest phytate, the major form of phosphorus in plant-based feeds. Consequently, this enzyme is supplemented in these species' diets to decrease their phosphorus excretion, and it has emerged as one of the most ef...

Dihydrolipoamide dehydrogenase: a 'new' function for an old enzyme?

GSK-3: new thoughts on an old enzyme.

Over the past decade, a serine–threonine kinase first characterized for its role in glycogen metabolism has shown itself to be a key player in numerous processes, in organisms ranging from yeast to mammals (reviewed in Yost et l., 1997). Glycogen synthase kinase-3 was originally idenified as a constitutively active kinase that is inactivated in esponse to extracellular signals. However, it is n...