Peptides from bovine brain: structure and biological role

Abstract

Fractionation of bovine brain extracts followed by automatic Edman sequencing of individual components resulted in identification of 107 endogenous peptides formed from functional proteins (haemoglobin, myelin basic protein, cytochrome c oxidase, etc) or unknown precursors. Several of the newly identified brain peptides demonstrate different types of biological activity; some of the substances show considerable overlap with the known biologically active peptides. It is suggested that these peptides should participate in regulation of extracellular and intracellular biochemical processes. A concept of 'tissue-specific peptide pool' is formulated describing a novel system of peptidergic regulation, complementary to the conventional hormonal and neuromodulatory systems. According to that description functional proteins provide their proteolytically derived fragments for maintaining the tissue homeostasis by modulating the availability of peptide receptors to respective 'true' ligands.

A novel system of peptidergic regulation

“…Analogously, the content of neokyotorphin in rat lung tissue is 10–15‐fold higher than in the rat brain [21]. Brain extracts also contain fragments of neurospecific proteins [15, 16], the spleen extract is enriched with fragments of β‐actin [26].…”

“…In particular, a novel family corresponding to the (84–95) segment of the hemoglobin α‐chain was discovered in the supernatant, as well as a novel pattern of formation of the peptides corresponding to β‐chain segment (12–31). The related family found in bovine brain extract [15]is formed upon cleavage of β‐globin (14–28) at the Asp 20 –Glu 21 site giving rise to two groups of both N‐ and C‐terminally shortened peptides. In contrast, in the erythrocytes the tertiary splitting takes place at Val 11 –Thr 12 (instead of Leu 13 –Trp 14 ) and the resultant fragments are in turn cleaved at two sites (Val 17 –Asn 18 and Asp 20 –Glu 21 ) forming two families of overlapping peptides.…”

Peptides comprising the bulk of rat brain extracts: isolation, amino acid sequences and biological activity

“…The elution profiles from individual brain specimens were highly reproducible, proving the stability of the peptide composition of brain tissue, analogous to the peptide panels of bovine brain [1,2] and cerebellum [7,18,19] extracts. The typical chromatograms of the fractions I -IV are given in Figures 2 -5.…”

“…Structural analysis of the low molecular weight components of bovine brain [1,2] and red bone marrow [3] extracts, lysate of human erythrocytes [4,5], extract of rat brain [6] and human cerebellum [7] has demonstrated that these sources mainly contain the fragments of functional proteins, in particular, hemoglobin. The number of components corresponding to chromatographic peaks, distinguishable in the chromatograms varies from 15 -25 to 800-1500, i.e.…”

“…In this work the analysis of peptide components of rat brain is described and the data is compared with those of bovine brain [1]. …”