Sequential Formation of Beta-Endorphin-Related Peptides in Porcine Pituitary

Smyth, Derek G.; Darby, Nigel J.; Maruthainar, Kamala

doi:10.1159/000124931

Cited by 10 publications

(5 citation statements)

References 11 publications

(13 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is in harmony with a recent study of proteolytic processing reactions in pro-opiomelanocortin which showed that the cleavage reactions that product the different forms of fl-endorphin do not occur in a competitive manner but follow a time-ordered sequence, each step going to completion before the next commences [18]. Together, the results of these two investigations support a concept that prohormone processing reactions take place in discrete, individually distinct stages.…”

supporting

confidence: 85%

Sequential processing reactions in the formation of hormone amides

Bleakman¹,

Smyth²

1987

European Journal of Biochemistry

Self Cite

View full text Add to dashboard Cite

The substrate specificity of an enzyme with amidating activity, present in porcine pituitary, was investigated by examining its ability to convert the synthetic peptides D-Tyr-Val-Gly and D-Tyr-Val-Gly-Lys-Arg to the dipeptide amide ~-T y r -v a l -C o N H~. The purified enzyme catalysed the amidation reaction with the tripeptide but did not accept the pentapeptide as a substrate. With the mixture of enzymes present in a membrane fraction from porcine pituitary or the enzymes in a secretory granule fraction, both the tripeptide and pentapeptide substrates gave rise to D-Tyr-Val amide; the formation of dipeptide amide from the pentapeptide, however, involved a latency period after which amidation occurred at a similar rate with the two substrates. Evidence was obtained that arginine and lysine were released from the C terminus of the pentapeptide before amidation took place since the rate of formation of dipeptide amide was reduced at pH values that were compatible with amidation but unfavourable to the action of carboxypeptidase H. In addition formation of the dipeptide amide from the pentapeptide was blocked by guanidinoethylmercaptosuccinic acid and glycylarginine, which are inhibitors of carboxypeptidase enzymes.The experiments demonstrate that removal of basic residues from the C terminus of a peptide and amidation at C-terminal glycine are reactions that take place consecutively. These prohormone-processing reactions, which are intrinsic to the formation of hormone amides, did not synergise.The a-amide group of hormone amides is known to be biosynthesised by an enzyme-cdtalysed reaction which involves oxidation of peptides linked to glycine [l, 21. Knowledge of the specificity of the reaction was first gained from studies with synthetic substrates when it was shown that peptides terminating in alanine, leucine, sarcosine, glutamic acid and lysine were not susceptible to amidation whereas peptides terminating in glycine or D-alanine gave rise to the des-glycine or des-D-alanine peptide amide [2, 31. Notably a peptide terminating in the sequence glycyllysine did not undergo amidation, indicating that a glycine COOH group is important for the reaction. These observations, together with the studies of Suchanek and Kreil on the biosynthesis of mellitin [4], have established that a C-terminal glycine residue is essential for enzyme-catalysed amidation and this has been supported by a growing body of evidence that the biosynthetic precursors of hormone amides invariably contain glycine immediately adjacent to the hormone sequence. It has not been established, however, whether the enzyme or enzymes that are involved in amidation might act synergistically with the endopeptidases and exopeptidases that are involved in cleavage and trimming of the prohormone peptide chain prior to the amidation reaction.In a recent study it was reported that a hexapeptide GlpHis-Pro-Gly-Lys-Arg (Glp, pyrrolidonecarboxylyl), which is related to the prohormone of thyrotropin-releasing hormone (TRH) [5], was converted to Glp-His-Pro amid...

show abstract

supporting

confidence: 85%

Sequential processing reactions in the formation of hormone amides

Bleakman¹,

Smyth²

1987

European Journal of Biochemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…An interesting question was: do the different peptides released from their precursors remain in the same compartment in the secretory granule where the processing reactions occur or do the different processing reactions take place independently in a regimented manner? Evidence was obtained by extracting lipotropin and peptides related to β-endorphin from the anterior pituitary and pars intermedia of the pituitary and then resolving them by gel exclusion and cation exchange chromatography (Smyth et al 1988). It was envisaged that possible heterogeneity in the structure of lipotropin would be revealed by identifying its C-terminal fragment released by trypsin, cleavage being restricted to the COOH group of arginine at position 60 of the lipotropin sequence, achieved by protecting the ε-NH 2 groups of lysine reversibly by citraconylation.…”

Section: T20 Thematic Review D G Smythmentioning

confidence: 99%

60 YEARS OF POMC: Lipotropin and beta-endorphin: a perspective

Smyth

2016

Journal of Molecular Endocrinology

View full text Add to dashboard Cite

Many important fields of research had a humble origin. In the distant past, A J P Martin's discovery that amino acids could be separated by paper chromatography and Moore and Stein's use of columns for quantitative amino acid analysis provided the first steps towards the determination of structure in complex biologically active molecules. They opened the door to reveal the essential relationship that exists between structure and function. In molecular endocrinology, for example, striking advances have been made by chemists with their expertise in the identification of structure working with biologists who contributed valuable knowledge and experience. Advantage was gained from the convergence of different background, and it is notable that the whole is greater than the sum. In the determination of structure, it may be recalled that four of the world's great pioneers (Archibald Martin, Rodney Porter, Fred Sanger and Vincent du Vigneaud) were acknowledged for their fundamental contributions when individually they were awarded the Nobel Prize. They foresaw that the identification of structure would prove of outstanding importance in the future. Indeed, study of the structures of β-endorphin and enkephalin and the different forms of opiate activity they engender has led to a transformation in our understanding of chemical transmission in the brain.

show abstract

“…In these cells, processing of POMC results in the generation of pro‐γ‐MSH, ACTH and β‐LPH, with little processing to the smaller peptides. This pattern of processing also occurs in the anterior pituitary (27–29), although a significant proportion of the β‐LPH is further cleaved to β‐endorphin (30, 31). There is some evidence to suggest that, in the rat and the sheep, a proportion of the ACTH is cleaved to α‐MSH and CLIP.…”

Section: Anterior Lobementioning

confidence: 99%

“…ACTH is cleaved to α‐MSH and CLIP whereas β‐LPH is virtually completely processed to β‐endorphin and γ‐LPH (28, 32). β‐endorphin 1‐31 is cleaved at the C‐terminus to give β‐endorphin 1‐27 , β‐endorphin 1‐26 and a dipeptide glycylglutamine (31). The majority of the β‐endorphin is N ‐acetylated (27, 33), which destroys its opiate activity (34).…”

Section: Intermediate Lobementioning

confidence: 99%

The Tissue‐Specific Processing of Pro‐Opiomelanocortin

Bicknell

2008

J Neuroendocrinology

117

View full text Add to dashboard Cite

In 1967, a new era in endocrinology was born. A set of pulse chase experiments performed by Steiner and Oyer (1) elegantly showed, for the first time, that insulin was derived from a larger precursor molecule, proinsulin. The radical revelation, that bioactive peptides are derived from larger precursors, forever changed endocrinology and, from then on, the concept of hormone precursors (or prohormones) has become a central dogma. Subsequently, the use of both traditional protein sequence studies and recombinant DNA technology have provided definitive structures for the precursors of all the known bioactive peptides as well as identifying several previously unknown precursors, the function of which are still not fully understood. In general, all these molecules contain within their sequence one or more copies of the active peptide while some contain several different bioactive peptides. In addition, they undergo a series of highly regulated post-translational events that includes specific proteolytic cleavage and modifications such as amidation, acetylation and phophorylation. These post-translational processing events are especially interesting because there are a number of examples where the extent of processing can yield very different bioactive peptides from the same precursor. Probably the best example of this phenomenon, and arguably the most studied prohormone, is the ACTH precursor pro-opiomelanocortin (POMC). This short review aims to highlight why it has been of such interest to (neuro)endocrinologists and suggests that it still has a few more secrets to yield. Discovery of POMCThe discovery of POMC ( Fig. 1) was preceded by a number of what, at the time, appeared to be unrelated observations. Both ACTH and a-melanocyte-stimulating hormone (a-MSH) had been purified and sequenced from the pituitaries of various species. However, the fact that a-MSH has the same amino acid sequence as the first 13 residues of ACTH was not seen to be of much significance until the isolation of corticotrophin-like intermediate peptide (CLIP) (2), the peptide that comprises the C-terminal of ACTH. This, together with the identification of larger molecular weight forms of immunoreactive ACTH (3, 4), began to suggest that ACTH and a-MSH were indeed derived from the same molecule.A further observation suggesting the existence of a common precursor to a number of pituitary hormones was that the sequence of the newly-discovered pituitary peptide, b-endorphin (5, 6), which had strong opiate-like activity, shared the same sequence as the C-terminal of b-lipotrophin (b-LPH), another pituitary hormone released under the same conditions as ACTH. It was subsequently shown that b-LPH was expressed in the same pituitary cells as a-MSH and CLIP (7).In 1976, the first published report came that suggested ACTH and b-LPH were derived from the same molecule (8) It is just over 30 years since the definitive identification of the adrenocorticotrophin (ACTH) precursor, pro-opiomelanocotin (POMC). Although first characterised in the anterior and...

show abstract

Sequential Formation of Beta-Endorphin-Related Peptides in Porcine Pituitary

Cited by 10 publications

References 11 publications

Sequential processing reactions in the formation of hormone amides

Sequential processing reactions in the formation of hormone amides

60 YEARS OF POMC: Lipotropin and beta-endorphin: a perspective

The Tissue‐Specific Processing of Pro‐Opiomelanocortin

Contact Info

Product

Resources

About