Which LD isoenzyme is the most labile, losing activity more rapidly at lower temperatures?

Lactate dehydrogenase (LD) is an enzyme that exists in different isoenzymes, each with varied stability and susceptibility to changes in environmental conditions, including temperature. LD-5 is notably the most labile isoenzyme among the five, exhibiting a tendency to lose activity more rapidly at lower temperatures.

This increased lability is attributed to its structural characteristics, which make it less stable compared to the other isoenzymes. In laboratory settings, when samples containing LD-5 are stored at lower temperatures, there is a significant risk of decreased enzyme activity, potentially leading to inaccurate assay results. This characteristic is important for clinical laboratories to consider when processing samples for LD isoenzyme analysis. Ensuring proper handling and storage conditions can help maintain enzyme activity, particularly for LD-5, to provide accurate diagnostic information.

Other isoenzymes like LD-1 and LD-2, while also important, maintain greater stability at varying temperatures. Therefore, recognizing LD-5 as the most labile isoenzyme guides laboratory practices in sample management and analysis.