H, C, and N resonance assignments of the amyloidogenic peptide SEM2(49-107) by NMR spectroscopy.

It has been shown that human seminal fluid is a major factor in enhancing HIV activity. The SEM2(49-107) peptide is a product of cleavage after ejaculation by internal prostheses of the semenogelin 2 protein, expressed in seminal vesicles. It is established that the peptide SEM2(49-107) forms amyloid fibrils, which increase probability of contracting HIV infection.

PAP(248-286) Conformational Changes during the Lag Phase of Amyloid Fibril Formation.

The initial stage of fibril formation of C-terminal region PAP(248-286) of human seminal plasma protein prostatic acid phosphatase was considered. Amyloid fibrils from the peptide PAP(248-286) are termed as a semen-derived enhancer of viral infection (SEVI) found in abundant quantities in semen. The kinetics of the amyloid fibril formation process consists of two characteristic phases (lag phase/nucleation phase and growth phase/elongation phase).

Extent of N-Terminus Folding of Semenogelin 1 Cleavage Product Determines Tendency to Amyloid Formation.

It is known that four peptide fragments of predominant protein in human semen Semenogelin 1 (SEM1) (SEM1(86-107), SEM1(68-107), SEM1(49-107) and SEM1(45-107)) are involved in fertilization and amyloid formation processes. In this work, the structure and dynamic behavior of SEM1(45-107) and SEM1(49-107) peptides and their N-domains were described. According to ThT fluorescence spectroscopy data, it was shown that the amyloid formation of SEM1(45-107) starts immediately after purification, which is not observed for SEM1(49-107).