Mechanism for condensation reactions of amino acids It is well known that peptides are synthesized by a so called &quot;condensation&quot; reaction between an amine and a carboxylic acid group to form the final amide moiety (because it releases water). In its general form, it resembles the picture below.

However, what is the actual chemical mechanism behind this reaction? My thoughts are that the amine can deprotonate the carboxylic acid and form a carboxylate - which is a very bad electrophile - so how would it form the amide from nucleophilic attack? I am aware that in the body, it is possible that this reaction is mediated by biochemical catalysts but I am still not sure of the overall mechanism. If this reaction does indeed involve biochemical catalysts, is it possible to complete the synthesis without them?
Here is a proposed mechanism in a 2005 paper. One thing to point out is that this is a proposed mechanism but it is all I could find:

link to pdf: https://www.pnas.org/content/pnas/102/35/12395.full.pdf
Typically, these reactions involve the nitrogen attacking the partially positive carbonyl carbon as a form of nucleophilic substitution. However, OH is a bad leaving group so often, reagents such as DCC can be used to make the OH into a good leaving group before reacting. This is why it is easier to make nylon using a diacid chloride instead of a diacid.