Pyroglutamyl N-termini of thermal polyamino acids

Area of Science:

• Biochemistry
• Polymer Chemistry

Background:

• Previous indirect methods suggested pyroglutamic acid at the N-termini of thermal polyamino acids.
• These polyamino acids are composed of various amino acids including Ala, Gly, Glu, Leu, Phe, and Pro.

Purpose of the Study:

• To directly determine the presence of pyroglutamic acid at the N-termini of thermal polyamino acids.
• To investigate the composition and structure of polyamino acids formed under thermal conditions.

Main Methods:

• Direct enzymatic assay using pyrrolidone carboxylyl peptidase to cleave N-terminal pyroglutamyl residues.
• Indirect methods including trifluoroacetic acid hydrolysis and alkaline hydrolysis.
• Analysis of amino acid composition of polyamino acids.

Main Results:

• Directly confirmed pyroglutamic acid as the N-terminal residue in thermal polyamino acids.
• Identified a diverse range of amino acids (Glu, Asp, Ala, Gly, Ile, Pro, Val) in the polyamino acid chains.
• Observed various amino acids penultimate to the N-terminal pyroglutamic acid, suggesting complex structures.

Conclusions:

• Pyrrolidone carboxylyl peptidase provides a direct method for identifying N-terminal pyroglutamic acid in polyamino acids.
• The presence of pyroglutamic acid and diverse penultimate amino acids indicates complex polypeptide formation and potential for varied structures.