In organic chemistry, proton transfers are "free". if you are in a protic environment, whether the solvent or reagent, you can not really determine where the proton comes from. It is not vital to know where it comes from, it just does.

HI, just a quick note althought I agree with Charles comment I believe that maybe more can be said if it is known what type of esterificatiion we talking about: in a biologic environment, a cell ? an isolated enzimatic system? or one of the many possible organic methods, and which one?

Thanks. I was asking about esterification processes within a cell.

In the process of tryacylglycerol synthesis in the cell, glycerol is not directly esterified by fatty acids. It is a acyltransfer reaction between either glycerol phosphate in most cells and dihydroxyacetone phosphate in adepose cells, followed by acyltransfer reactions in two subsequent steps. Here the H+ of fatty acid is replaced by CoA with formation of AcylCoA and the fattyacyl component of the fatty acyl CoA is transfered to glycerol by formation of the ester bond by removing the H (not H+) from the OH of glycerol. This is very complicated multistage enzyme catalyzed reaction involving a group of enzyme. In reality, there are multiple series of neucleophilic attack generated by the enzyme protein finally ending up with formation of the ester bond, where we cannot really trace the origin and final fate of the hydrogens in glycerol and fatty acid.

Please go through the stages of triacylglycerol biosynthesis and mechanism of metabolic acyltransfer reaction and acyltransferase activity.

Thanks Ranadeep! Though we cannot fully understand, we can appreciate this very complicated process! I was wondering how our (human) skin oils are formed, and I guessed that it's mainly triglycerides.

Thanks to all of you!

To know more about skin oils, please go through the link :

http://fx.damasgate.com/composition-of-human-sebum/