Related Experiment Video

Updated: May 26, 2026

Genetic and Biochemical Approaches for In Vivo and In Vitro Assessment of Protein Oligomerization: The Ryanodine Receptor Case Study
12:43

Genetic and Biochemical Approaches for In Vivo and In Vitro Assessment of Protein Oligomerization: The Ryanodine Receptor Case Study

Published on: July 27, 2016

Microbial transglutaminase-induced structural and rheological changes of cationic and anionic myofibrillar proteins

Geun-Pyo Hong1, Youling L Xiong

  • 1Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40546-0215, USA.

Meat Science
|January 7, 2012
PubMed

Insights

Microbial transglutaminase (TG) cross-linking of porcine myofibrillar protein (MP) is pH-dependent. TG primarily deamidates MP at low pH, with cross-linking occurring only at higher pH levels.

Area of Science:

  • Food Science
  • Protein Chemistry
  • Biochemistry

Background:

  • Myofibrillar protein (MP) is crucial in meat texture.
  • Microbial transglutaminase (TG) modifies protein structure.
  • Understanding TG's effect on MP under different conditions is important for food processing.

Purpose of the Study:

  • To investigate the impact of pH and ionic strength on microbial transglutaminase (TG) activity on porcine myofibrillar protein (MP).
  • To determine the specific reactions (deamidation vs. cross-linking) catalyzed by TG under varying conditions.
  • To assess the influence of these reactions on MP's structural and rheological properties.

Main Methods:

  • Studied porcine MP under pH 2.0-6.0 and ionic strengths of 0.1M and 0.6M NaCl.
  • Utilized surface hydrophobicity measurements and differential scanning calorimetry to assess protein unfolding.
  • Employed SDS-PAGE and dynamic rheology to evaluate protein cross-linking and structural changes.
  • Analyzed carboxyl group content to differentiate between deamidation and cross-linking.

Main Results:

  • Protein unfolding occurred below myosin's isoelectric point (pI) at low pH.
  • TG failed to cross-link MP at low ionic strength (0.1M NaCl) and pH 3.0, despite high solubility.
  • TG-catalyzed deamidation was dominant below pH 5.0, while cross-linking occurred at higher pH.
  • Deamidation did not significantly alter the rheological properties of MP.

Conclusions:

  • The pH of the substrate protein dictates the reaction pathway of microbial transglutaminase (TG).
  • TG activity on porcine myofibrillar protein (MP) is strongly influenced by pH, favoring deamidation at low pH and cross-linking at higher pH.
  • Protein solubility correlates with TG reaction intensity, but cross-linking is limited under specific low pH and low ionic strength conditions.

More Related Videos

Immunolabelling Myofiber Degeneration in Muscle Biopsies06:37

Immunolabelling Myofiber Degeneration in Muscle Biopsies

Published on: December 5, 2019

Related Concept Videos

Studying the Cytoskeleton01:17

Studying the Cytoskeleton

The cytoskeletal architecture can be studied using different microscopic and biochemical techniques. Electron microscopy was instrumental in discovering the cytoskeletal architecture around the 1960s, which allowed obtaining structural information at a high-resolution level. However, the sample preparation procedure often limits this ability in biological samples. Several protocols have been developed over the years to optimize sample preparation. In one of the protocols known as rotary...
Bacterial Protein Maturation01:26

Bacterial Protein Maturation

Bacterial protein maturation is a tightly regulated process that ensures newly synthesized polypeptides achieve correct functional conformations. This maturation involves a series of modifications, folding events, and quality control steps, often assisted by specialized chaperone proteins.N-Terminal ModificationsThe maturation of bacterial polypeptides begins cotranslationally as the polypeptide exits the ribosome. The first amino acid, N-formylmethionine (fMet), is typically modified at the...