English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Flexible loops, often referred to as flaps, have been shown to play a role in catalytic mechanisms of different enzymes. Flaps at the active site regions have been observed in the crystal structures of aspartic proteinases and their residues implicated in the catalytic processes. This research investigated the role of the flap residue, threonine 77, in the activation of pepsinogen and the catalytic mechanism of pepsin. Three mutants, T77S, T77V and T77G, were constructed. Differences in amino acid polarity and hydrogen bonding potential were shown to have an influence on the activation and catalytic processes. T77S activated at the same rate and had similar catalytic parameters as the wild-type pepsin. The activation rates of T77V and T77G were slower and their catalytic efficiencies lower than the wild-type. The results demonstrated that the threonine 77 polar side chain played a role in a proteolysis. The contribution of the side chain to zymogen activation was associated with the proteolytic cleavage of the prosegment. It was postulated that the hydroxyl group at position 77 provided an essential hydrogen bond that contributed to proper substrate alignment and, indirectly, to a catalytically favorable geometry of the transition state.

The role of the flap residue, threonine 77, in the activation and catalytic activity of pepsin A