Histidine
Histidine — An essential amino acid (His, H) with an imidazole side chain that can be protonated at physiological pH, important in enzyme catalysis and metal binding.
What Is Histidine?
Histidine (His, H) is the only amino acid with a side-chain pKa near physiological pH (pKa ~6.0), making it uniquely able to switch between protonated (positively charged) and neutral states under biological conditions (MW: 155.16 Da). This property makes histidine essential for enzyme catalysis, pH sensing, and metal coordination.
Roles in Peptide Research
- Metal coordination: Histidine imidazole coordinates zinc, copper, and iron. Essential for the GHK-copper complex
- pH-responsive: Histidine-containing peptides can be designed to change conformation or binding at different pH values
- Buffer component: Histidine is used as a formulation buffer (pH 5.5-7.0) for peptide products
- Purification tag: Polyhistidine (His6) tags enable immobilized metal affinity chromatography purification
Frequently Asked Questions
What is Histidine?
An essential amino acid (His, H) with an imidazole side chain that can be protonated at physiological pH, important in enzyme catalysis and metal binding.
Why is Histidine important in peptide research?
Histidine 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.