function of l-carnitine in the body Didn't another study show carnitine was good for heart? L-Carnitine Benefits, Sources, and Side

This insufficient propionyl-CoA labeling hindered our ability to glean information about the metabolic flux from propionyl-CoA into the TCA cycle and beyond

J Investig Med

To overcome the selectivity issues of native lysine reactivity, researchers have developed genetic code expansion technologies to introduce non-natural lysine derivatives (such as lysine analogs bearing azide, alkyne, or tetrazine groups) at specific sites in proteins

This is also one of the reasons why carnitine supplements are very popular with sportspeople, as are certain essential amino acids such as branched-chain amino acids (leucine, isoleucine, and valine)