Arginine
Arginine — A conditionally essential amino acid (Arg, R) with a guanidinium side chain. Plays key roles in nitric oxide synthesis, cell division, and immune function.
What Is Arginine?
Arginine (Arg, R) is a positively charged amino acid with a guanidinium side chain (pKa ~12.5, MW: 174.20 Da). It carries a permanent positive charge at all physiological pH values, making it essential for electrostatic interactions, membrane binding, and nuclear localization signals. Arginine-rich sequences are the basis for cell-penetrating peptides.
Roles in Peptide Research
- Cell penetration: Polyarginine (R8, R9) and TAT peptide (RKKRRQRRR) are the most effective CPP sequences
- Receptor binding: RGD (Arg-Gly-Asp) motif binds integrins. Arg residues form salt bridges with receptor Asp/Glu residues
- Solubility: Arginine hydrochloride (0.5-1 M) is used as an aggregation suppressor for hydrophobic peptides
- Synthesis challenge: Pbf protecting group requires extended TFA cleavage time (3-4 hours) for complete removal
Frequently Asked Questions
What is Arginine?
A conditionally essential amino acid (Arg, R) with a guanidinium side chain. Plays key roles in nitric oxide synthesis, cell division, and immune function.
Why is Arginine important in peptide research?
Arginine is a fundamental concept in amino acid as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.