Allantoate amidohydrolase (AAH)

Allantoate amidohydrolase (AAH) is an enzyme that catalyzes the hydrolytic cleavage of allantoate to produce ureidoglycolate, carbon dioxide, and ammonium, playing a crucial role in nitrogen recycling during purine catabolism, especially in plants[1][2][5][8][9][10]. It forms homodimers and is typically activated by manganese ions in vivo, with its activity being inhibited by fluoride, borate, L-asparagine, and L-aspartate[2][8]. In the plant purine degradation pathway, AAH is essential for providing nitrogen under conditions where other sources are low, and is localized to the endoplasmic reticulum, following the generation of allantoin in the peroxisome[2][8]. Structurally, it shares similarity with zinc exopeptidases in the peptidase M20 family, but displays unique active site architecture to differentiate it from other amidohydrolases[1][3]. In plants, knockout mutations of AAH result in impaired ability to utilize allantoin as a nitrogen source, emphasizing its central metabolic function[5][8][10]. The enzyme is not directly targeted by therapeutic drugs and has no established role as a disease biomarker or safety concern in human medicine; rather, its importance lies primarily in plant biology and nitrogen metabolism[2][5][8].

Other names

Allantoate amidinohydrolaseAllantoate deiminase