Fatty acid specificity of glyceride synthesis by homogenates of bovine mammary tissue

Fatty acid esterification by cell free preparations of bovine mammary tissue was investigated to determine if the type of long chain fatty acid supplied might influence the rate of triglyceride synthesis by that tissue. Homogenates of lactating bovine mammary tissue esterified¹⁴C-fatty acids into glycerides at rates dependent upon chain length and degree of unsaturation. Palmitic, stearic, oleic and linoleic acids were esterified at rates consistent with their concentration in milk fat. A comparison of free fatty acid concentrations of mammary tissue with levels saturating esterification suggested that supply of fatty acids does not limit glyceride synthesis. Certain combinations of fatty acids were facilitory, competitive or inhibitory to esterification. Stearic acid complimented esterification of palmitic and oleic acids. Unlabeledtrans-11-octadecenoic acid did not compete with¹⁴C-palmitate as efficiently in the esterification process as did unlabeledcis-9-octadecenoic acid, indicating that the mammary gland may preferentially esterify thecis-isomer of C-18∶1. Linoleic acid inhibited esterification of palmitic, stearic and oleic acids. Michigan Agricultural Experiment Station Journal Article No. 5100.