Nitric oxide synthase in beef semimembranosus muscle during postmortem aging

Area of Science:

• Food Science
• Biochemistry
• Muscle Biology

Background:

• Nitric oxide synthase (NOS) plays a role in various physiological processes.
• Understanding NOS activity during postmortem aging is crucial for meat quality.
• Limited data exists on NOS in beef muscle postmortem.

Purpose of the Study:

• To investigate the activity, expression, and localization of NOS in beef semimembranosus (SM) muscle during postmortem aging.
• To determine the role of calpain in nNOS degradation.
• To analyze S-nitrosothiol (SNO) changes during aging.

Main Methods:

• Beef SM muscles were vacuum-packaged and aged at 4°C for 1, 3, 7, and 14 days.
• NOS activity assays were performed.
• Neuronal NOS (nNOS) content was measured using Western blotting.
• Immunofluorescence was used for nNOS localization.
• S-nitrosothiol (SNO) content was quantified.

Main Results:

• NOS activity was maintained throughout the 14-day aging period.
• NOS activity and nNOS content significantly decreased at 3 and 7 days compared to 1 day.
• Calpain was identified as a key enzyme in nNOS degradation.
• nNOS was primarily localized in the sarcolemma.
• SNO content significantly increased at 1, 3, and 7 days post-slaughter.

Conclusions:

• This study provides the first evidence of NOS activity and expression dynamics in beef during postmortem aging.
• Calpain-mediated degradation of nNOS impacts its levels during aging.
• Increased SNO content suggests a role in postmortem changes in beef muscle.