Transglutaminase Enzymes Crosslink Proteins

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Biological Strategy

Mammals

AskNature Team

Image: Leonard von Bibra / Unsplash / Free non-commercial use

Chemically Assemble Polymers

We might think that complex polymers are the result of human industrial ingenuity, but nature cornered the market on polymers billions of years earlier. Examples of biopolymers are proteins, carbohydrates, and genetic material. In contrast to human industrial processes, within a cell, ribosomes covalently bond amino acids together to form proteins.

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Catalyze Chemical Breakdown

Life depends upon the building up and breaking down of biological molecules. Catalysts, in the form of proteins or RNA, play an important role by dramatically increasing the rate of a chemical transformation––without being consumed in the reaction. The regulatory role that catalysts play in complex biochemical cascades is one reason so many simultaneous chemical transformations can occur inside living cells in water at ambient conditions. For example, consider the 10-enzyme catalytic breakdown and transformation of glucose to pyruvate in the glycolysis metabolic pathway.

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Mammals

Class Mammalia (“breast”): Bats, cats, whales, horses, humans

Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.

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Transglutaminase enzymes couple or crosslink proteins in organisms by catalyzing transamidation of glutamine and lysine residues.

Enzymes catalyze the cross-linking of natural polymers. Monomers (1) join together to form chains of polymers (2) that cross-link to form strong, large compounds (3). Artist: Emily Harrington. All rights reserved.

“Biology is well known for its use of linear polymers to perform sophisticated functions. Nucleic acids store and process genetic information, while proteins perform recognition, transport, and catalytic functions. Biology also employs polymers (especially proteins and polysaccharides) to perform mechanical functions and there are several examples in which biology covalently crosslinks polymers to confer elasticity and strength. In some cases, the crosslinking enzymes have attracted attention as a simple and safe means for macromolecular processing in vitro. Here, we review recent research with two enzymes, tyrosinase and microbial transglutaminase, that are being examined for a variety of applications.” (Yang et al. 2009:576)