Effects of Microgravity, Hypergravity, and Ionizing Radiation on the Enzymatic Activity of Proteinase K

TL;DR

This study explores how space-like conditions affect the activity of the enzyme proteinase K, finding that it remains functional and sometimes even more active under microgravity and hypergravity.

Contribution

The novelty lies in evaluating proteinase K's enzymatic activity under simulated space conditions, including microgravity, hypergravity, and ionizing radiation.

Findings

Proteinase K showed enhanced activity after 96 hours under simulated microgravity.

Hypergravity increased activity at low enzyme concentrations but reduced it at higher concentrations.

Gamma radiation caused a dose-dependent decline in proteinase K activity.

Abstract

Space conditions offer new insights into fundamental biological and molecular mechanisms. The study aimed to evaluate the enzymatic activity of proteinase K (PK) under extreme conditions relevant to space environments: simulated microgravity, hypergravity, and gamma radiation. PK activity was tested using azocasein (AZO) as a chromogenic substrate, with enzymatic reactions monitored spectrophotometrically at 450 nm. A rotating wall vessel (RWV) simulated microgravity, centrifugation at 1000× g (3303 rpm) generated hypergravity, and gamma radiation exposure used cesium-137 as the ionizing source. PK activity showed no remarkable changes under microgravity after 16 or 48 h; however, higher absorbance values after 96 h indicated enhanced AZO proteolysis compared to 1 g (Earth gravity) controls. In hypergravity, low PK concentrations exhibited slightly increased activity, while higher concentrations led to reduced activity. Meanwhile, gamma radiation caused a dose-dependent decline in PK activity; samples exposed to deep-space equivalent doses showed reduced substrate degradation. PK retained enzymatic activity under all tested conditions, though the type and duration of stress modulated its efficiency. The results suggest that enzyme-based systems may remain functional during space missions and, in some cases, exhibit enhanced activity. Nevertheless, their behavior must be evaluated in a context-dependent manner. These findings may be significant to advance biotechnology, diagnostics, and the development of enzyme systems for space applications.

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