Question

What is the predominant form of arginine atpH11? What is the second major species?

Short answer

The predominant form of Arginine at pH11 is HArg and the second major species is Arg-.

Step-by-step solution

Definition of Metallic elements and non-metallic elements

• 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.

Determine the predominant form of arginine at pH11 and what is the second major species

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" $\frac{\left[\mathrm{HArg}\right]}{\left[\mathrm{Arg}\right]}\approx 11:2$

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.