Final answer:
Mannosidase is an enzyme that cleaves mannose from glycans, crucial for glycoprotein turnover and dietary glycan breakdown, and functions in a biologically irreversible manner.
Step-by-step explanation:
Mannosidase is a type of enzyme that plays a crucial role in the degradation of complex sugars called glycans, particularly those containing the sugar mannose. Its primary function is to cleave the mannose molecules from the glycan structures. This process is essential for the normal turnover of glycoproteins within cells and for the breakdown of dietary glycans. While mannosidase is efficient at catalyzing the reaction it is designed for, it typically does not catalyze the reverse reaction. In other words, like many enzymes involved in metabolic processes, mannosidase acts in a biologically irreversible manner. This irreversibility ensures the unidirectional flow of certain metabolic paths which are valuable to the organism. For instance, the hexokinase enzyme which is also irreversible, is regulated allosterically to conserve the energy resource in the cell when its product, glucose-6-phosphate, is abundant.