Source:http://linkedlifedata.com/resource/umls/id/C0023689
MSH: A class of enzymes that catalyze the formation of a bond between two substrate molecules, coupled with the hydrolysis of a pyrophosphate bond in ATP or a similar energy donor. (Dorland, 28th ed) EC 6.,NCI: Major class of enzymes that catalyze the linking together of two molecules (EC class 6) for example DNA ligases that link two fragments of DNA by forming a phosphodiester bond. (On-line Medical Dictionary)