In enzymology, a xyloglucan 4-glucosyltransferase is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that catalyzes

Catalysis

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 the chemical reaction

Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

 in which a beta-D-glucosyl

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 residue is transferred from UDP-glucose to another glucose residue in xyloglucan

Xyloglucan

Xyloglucan is a hemicellulose that occurs in the primary cell wall of all vascular plants, however essential enzymes for xyloglucan metabolism, like XTH and β1→4-Glucan Synthase are found in Charophyceae algae. In many dicotyledonous plants, it is the most abundant hemicellulose in the primary cell...

, linked by a beta-1,4-D-glucosyl-D-glucose bond.

This enzyme belongs to the family of glycosyltransferase

Glycosyltransferase

Glycosyltransferases are enzymes that act as a catalyst for the transfer of a monosaccharide unit from an activated nucleotide sugar to a glycosyl acceptor molecule, usually an alcohol....

s, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-glucose:xyloglucan 1,4-beta-D-glucosyltransferase. Other names in common use include uridine diphosphoglucose-xyloglucan 4beta-glucosyltransferase, xyloglucan 4beta-D-glucosyltransferase, and xyloglucan glucosyltransferase.