Proteins are high molecular mass complex biomolecules of amino acids. The important proteins required for our body are enzymes, hormones, antibodies, transport proteins, structural proteins, contractile proteins etc. Except for glycine, all `alpha`-amino acids have chiral carbon atom and have L-configuration. The amino acids exists as dipolar ion called zwitter ion, in which a proton goes from the carboxyl group to the amino group. A large number of `alpha`-amino acids are joined by peptide bonds forming polypeptides. The peptides having very large molecular mass (more than 10,000) are called proteins. The structure of proteins is described as primary structure giving sequence of linking of amino acids, secondary structure giving manner in which polypeptide chains are arranged and folded, tertiary structure giving folding, coiling or bonding polypeptide chains producing three dimensional structures and quaternary structure giving arrangement of sub-units in an aggregate protein meolecule.
Which of the following statements is not correct?

Options

A. Amino acids exist as zwitter ions
B. All naturally occurring `alpha`-amino acids have `-NH_(2)` group on the right
C. Except glycine, all other naturally occuring `alpha`-amino acids have a chiral carbon atom.
D. The basic character in `alpha`-amino acids is due to the `-COO^(-)` group.

Answer

To determine which statement among the provided options is not correct regarding amino acids and proteins, we can analyze each statement step by step.

### Step 1: Analyze Statement 1
**Statement 1:** Amino acids exist in zwitterionic form.

**Analysis:** This statement is correct. Amino acids exist as zwitterions, which means they have both a positive and a negative charge, resulting from the proton transfer from the carboxyl group (-COOH) to the amino group (-NH2). This is a characteristic feature of amino acids in physiological pH.

### Step 2: Analyze Statement 2
**Statement 2:** All naturally occurring amino acids have NH2 group on their right.

**Analysis:** This statement is incorrect. In the Fischer projection, naturally occurring alpha-amino acids (except glycine) have the amino group (-NH2) on the left side, not the right. The L-configuration of amino acids indicates that the amino group is positioned on the left when the carboxyl group is at the top.

### Step 3: Analyze Statement 3
**Statement 3:** Except glycine, all other naturally occurring alpha amino acids have chiral carbon atoms.

**Analysis:** This statement is correct. Glycine is the only alpha-amino acid that does not have a chiral center because its side chain (R group) is a hydrogen atom, making it achiral. All other alpha-amino acids have a chiral carbon atom.

### Step 4: Analyze Statement 4
**Statement 4:** The basic character of alpha amino acids is due to the carboxylate group.

**Analysis:** This statement is misleading. The basic character of alpha-amino acids is primarily due to the amino group (-NH2), which can accept protons. However, in zwitterionic form, the amino group is protonated (-NH3+), and the carboxyl group exists as a carboxylate (-COO-). While the carboxylate can exhibit some basic characteristics in certain contexts, the primary basicity of amino acids is due to the amino group.

### Conclusion
Based on the analysis, the statement that is not correct is **Statement 2**: "All naturally occurring amino acids have NH2 group on their right."

### Final Answer
The incorrect statement is **Option 2**.

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