91Ó°ÊÓ

• Arginine, also known as l-arginine, is a -amino acid required for protein production.
• It consists of an amino group, a carboxylic acid group, and an aliphatic straight chain with three carbons that finishes in a side chain called guanidino group.

At the main form of Arginine as well as the second major species must be determined.

Given

$$\begin{gathered} \mathrm{pH}={\mathrm{pK}}_2=8.99,\left[{\mathrm{H}}_2{\mathrm{Arg}}^{+}\right]=\left[\mathrm{HArg}\right] \\ \mathrm{pH}={\mathrm{pK}}_3=12.1,\left[\mathrm{HArg}\right]=\left[{\mathrm{Arg}}^{-}\right] \end{gathered}$$

As a result, pH 11 , HArg is the most common species. owing to pH 11 be approximately two pH higher by one unit ${\mathrm{pK}}_2$,

The proportion ofrole="math" localid="1663415576398" $\frac{\left[\mathrm{HArg}\right]}{\left[\mathrm{Arg}\right]}≈11:2$

It may conclude that HArg accounts for the majority of arginine, with Arg- being the second most important species.

At pH 11, the most common form of arginine is HArg, with Arg- being the second most common species.