Can the oxidation of pyruvate to acetyl coa be called as acetylation in some ways? Please include credible sources in the answer.
Acetylation is defined as1:
Acetylation (or in IUPAC nomenclature ethanoylation) describes a reaction that introduces an acetyl functional group into a chemical compound.
So, any reaction in which an acetyl (CH3CO-) group adds to another compound is an acetylation reaction. A common example is Friedel-Crafts acetylation reaction:
If the reaction is catalyzed by pyruvate dehydrogenase: In this case, first of all the reaction that you refer to is termed as pyruvate decarboxylation (rather than oxidation, although it won't hurt either). As @WYSIWYG has said in comments, it is not a simple reaction, it involves three steps (+ 2 steps for regeneration of complex), each catalyzed by different enzymes. The name given for the whole complex is pyruvate dehydrogenase complex (PDC)2. The steps involved are3:
The keto carbon of pyruvate reacts with the carbanion of TPP on E1 to yield an addition compound. The electron-pulling positively charged nitrogen of the thiazole ring promotes loss of CO2. What remains is hydroxyethyl-TPP.
The hydroxyethyl carbanion on TPP of E1 reacts with the disulfide of lipoamide on E2. What was the keto carbon of pyruvate is oxidized to a carboxylic acid, as the disulfide of lipoamide is reduced to a dithiol. The acetate formed by oxidation of the hydroxyethyl moiety is linked to one of the thiols of the reduced lipoamide as a thioester.
The acetate is transferred from the thiol of lipoamide to the thiol of coenzyme A, yielding acetyl CoA.
Now, pyruvic acid has the formula: $CH_3-CO-COOH$. So, if you look at the step C of reaction, then since CH3CO- has been added to coenzyme A, hence, in a way, it would be considered an acetylation reaction. Pay attention that the complete reaction will not be considered acetylation, only a part of it would be. This is also the reason why calling the complete reaction as oxidation won't hurt, because even decarboxylation is just a part of complete reaction.
If the reaction is not catalyzed by pyruvate dehydrogenase Taking the question out from pyruvate dehydrogenase (as you don't talk specifically about that), there is an enzyme Acetyl-coA synthetase whose job is catalyzing acetylation of coenzyme-A(!)4. The reaction looks like this:
$ATP + acetate + co-A \rightarrow AMP + pyrophosphate + acetyl-coA$
The enzyme is of two types: AMP forming and ADP forming5:
So, as long as the conversion is not one specifically catalyzed by pyruvate dehydrogenase, we can say that Yes, conversion of coenzyme-A to Acetyl-coA is an acetylation reaction.
Hentchel KL, Escalante-Semerena JC. 15 July 2015. Acylation of biomolecules in prokaryotes: a widespread strategy for the control of biological function and metabolic stress. Microbiol Mol Biol Rev doi:10.1128/MMBR.00020-15