<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31316747</termId><termName>collagen</termName><termType>PT</termType><termNote><![CDATA[ The fibrous, extracellular matrix protein in skin, muscles, tendons, ligaments, and bone. Collagen is composed of repeating units of glycine-proline-hydroxyproline that form linear polypeptide chains; three chains are then twisted and interlocked with hydrogen bonding to form a rigid helix structure. Collagen-containing materials, such as hides, bones and fish, have been used to make animal glues since ancient times. Collagen will irreversibly hydrolyze, or denature, in hot water, forming a water-soluble gelatin. ]]></termNote><termCreatedDate>2026-03-30 20:25:17</termCreatedDate><relation><relationType>BT</relationType><termId>31303906</termId><termName>protein</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31340189</termId><termName>gelatin</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31340191</termId><termName>animal glue</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31320615</termId><termName>ossein</termName><termType>PT</termType></relation><relation><relationType>RT</relationType><termId>31374013</termId><termName>glue</termName><termType>PT</termType></relation><relation><relationType>RT</relationType><termId>31375599</termId><termName>bone</termName><termType>PT</termType></relation></term>  </Zthes>