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Peptidaser og enzymer involvert i proteinintoleranse

Vestn Ross Akad Med Nauk. 2007;(3):33-9.Links
[Regulatory peptides and psychomotor development in infants] [Article in Russian]
Sokolov OIu, Kost NV, Kurasova OB, Dmitriev AD, Gabaeva MV, Zolotarev IuA, Mikheeva IG, Zozulia AA.

Regulatory peptides (RP) are an important homeostatic factor. The maternal organism and placenta are substantial sources of RP for fetus during the prenatal period. Not only endogenous, but also exogenous RP play an important role during early postnatal period. In this study, the concentration of exogenous RP (casomorphins-7) and the activity of peptidases (enkephalinases) in the serum of breastfed and bottle-fed infants were estimated. Possible interrelation between these two parameters and the psychomotor development (PMD) of infants were evaluated. Using specially developed RIA, the investigators estimated the presence of human and bovine casomorphins immunoreactivity (CMir) in the serum of breastfed and bottle-fed infants. A distinct correlation of CMir with PMD was demonstrated. The activity of RP-degrading serum enzymes also correlated with PMD level. The role of endo- and exogenous peptides in normal PMD process and in the pathogenesis of early child autism is discussed in the article.

PMID: 17500212 [PubMed - indexed for MEDLINE]

Biol Chem. 2007 Mar;388(3):343-8.Links
Human dipeptidyl peptidase III acts as a post-proline-cleaving enzyme on endomorphins.
Barsun M, Jajcanin N, Vukelić B, Spoljarić J, Abramić M.
PLIVA Research and Development Ltd., Prilaz baruna Filipovića 25, 10000 Zagreb, Croatia.

Dipeptidyl peptidase III (DPP III) is a zinc exopeptidase with an implied role in the mammalian pain-modulatory system owing to its high affinity for enkephalins and localisation in the superficial laminae of the spinal cord dorsal horn. Our study revealed that this human enzyme hydrolyses opioid peptides belonging to three new groups, endomorphins, hemorphins and exorphins. The enzymatic hydrolysis products of endomorphin-1 were separated and quantified by capillary electrophoresis and the kinetic parameters were determined for human DPP III and rat DPP IV. Both peptidases cleave endomorphin-1 at comparable rates, with liberation of the N-terminal Tyr-Pro. This is the first evidence of DPP III acting as an endomorphin-cleaving enzyme.

PMID: 17338643 [PubMed - indexed for MEDLINE]

URN:ISBN:978-952-10-4087-0  2007-08-31
Blood pressure lowering effects of Lactobacillus helveticus fermented milk containing bioactive peptides Ile-Pro-Pro and Val-Pro-Pro; mechanistic, kinetic and clinical studies
Jauhiainen, Tiina, Helsingfors universitet, medicinska fakulteten, biomedicinska institutionen

The purpose of the present study was to evaluate the effects of Lactobacillus helveticus fermented milk (peptide milk) containing the casein-derived tripeptides Isoleucyl-prolyl-proline (Ile-Pro-Pro) and Valyl-prolyl-proline (Val-Pro-Pro) on blood pressure and vascular function in hypertensive subjects. The peptide milk lowered systolic and diastolic blood pressure in long-term use in hypertensive subjects when blood pressure was measured by using 24-hour ambulatory blood pressure measurement (ABPM). The blood pressure lowering effect was seen with the dose of 50 mg of tripeptides, and a tendency for lowering blood pressure was also observed when the dose was 5 mg. No adverse effects compared to the placebo group were reported or detected in laboratory analysis. The effect of the peptide milk on arterial stiffness was shown using two different methods, the ambulatory arterial stiffness index (AASI) and pulse wave analysis (PWA). According to the AASI, arterial stiffness was significantly reduced in the peptide milk group compared to the baseline level, but the difference was not significant compared to the placebo group. PWA showed that the peptide milk reduced arterial stiffness significantly compared to the placebo group. Endothelium-independent relaxation (nitroglycerin) and endothelium-dependent relaxation (salbutamol) did not differ between the groups. The blood pressure lowering mechanisms of the tripeptides and the kinetics of Ile-Pro-Pro were investigated using spontaneously hypertensive rats (SHR) and Sprague-Dawley rats. Previous studies have suggested that the blood pressure lowering effect of the tripeptides Ile-Pro-Pro and Val-Pro-Pro is based on angiotensin-converting enzyme inhibition, but the present findings did not agree with these previous studies. It was shown in SHR that calcium, potassium and magnesium may also have an important role in attenuating the development of hypertension as part of the peptide milk effect. In addition, the present study suggests indirectly that improved endothelial nitric oxide release capacity is not the mechanism by which peptide milk mediates its favourable circulatory effects.

The kinetics of Ile-Pro-Pro were studied using adult Sprague-Dawley rats. The results showed that orally administered Ile-Pro-Pro is absorbed at least partly intact from the gastrointestinal tract. Radiolabelled Ile-Pro-Pro was distributed in different tissues and considerable radioactivity levels were found in tissues related to the renin-angiotensin system (RAS), adrenals, aorta and kidneys. Ile-Pro-Pro does not bind to plasma proteins, and therefore it is possible that its blood pressure lowering effect is mediated by free Ile-Pro-Pro. In conclusion, consumption of the peptide milk lowers blood pressure and reduces arterial stiffness in hypertensive subjects. Ile-Pro-Pro can be absorbed partly intact from the gastrointestinal tract and might accumulate in tissues related to the RAS. The precise blood pressure lowering mechanism of peptide milk remains to be studied.

[URL til artikkel]

J Protein Chem. 2003 Nov;22(7-8):601-6.Links
Biochemical and pharmacological aspects of two bradykinin-potentiating peptides obtained from tryptic hydrolysis of casein.
Perpetuo EA, Juliano L, Lebrun I. Laboratory of Biochemistry and Biophysics, Butantan Institute, Av Vital Brazil 1500, São Paulo, SP, 05503-900, Brazil.  

Peptides that display bradykinin-potentiating activity have been obtained from a number of distinct sources, such as snake venoms, fibrinogen, and casein. This paper describes the characterization of two new peptides generated by tryptic hydrolysis of casein. No homology was found with other known vasoactive or vasopotentiating peptides, especially by the lack of Ile-Pro-Pro motif. The peptides EMPFPK and YPVEPFTE, corresponding to the gamma casein sequence (108-113 and 114-121, respectively), displayed a selective potentiating activity on isolated guinea pig ileum for bradykinin. Besides, the octapeptide YPVEPFTE showed an in vitro competitive inhibitor effect on angiotensin-converting enzyme and thimet oligopeptidase and presented an opiate-like activity, increasing two times the latence time in the hot-plate assay. The results suggest that the isolated bioactive peptides act on conversion and/or inactivation of endogenous peptides by enzymes such as angiotensin-converting enzyme and thimet oligopeptidase by modifying several systemic responses such as blood-pressure regulation and in pain response.

PMID: 14714726 [PubMed - indexed for MEDLINE]

J Biol Chem. 1990 Jan 25;265(3):1476-83.Links
Hydrolysis and transport of proline-containing peptides in renal brush-border membrane vesicles from dipeptidyl peptidase IV-positive and dipeptidyl peptidase IV-negative rat strains.
Tiruppathi C, Miyamoto Y, Ganapathy V, Roesel RA, Whitford GM, Leibach FH.
Department of Cell and Molecular Biology, Medical College of Georgia, Augusta 30912-2100.

In this investigation, we have demonstrated that the renal brush-border membrane of Fischer 344 rats from the Japanese Charles River Inc. specifically lacks dipeptidyl peptidase IV (DPP IV) activity, whereas the renal brush-border membrane of Fischer 344 rats from three different sources within the United States possesses normal levels of DPP IV activity. Comparison of the brush-border proteins between Charles River (U.S.A.) Fischer 344 rats (DPP IV positive) and Japanese Charles River Fischer 344 rats (DPP IV negative) revealed that a protein band (Mr=100,000), apparently identical with DPP IV, was absent in the membranes from Japanese Charles River Fischer 344 rats. We examined the handling of radiolabeled beta-casomorphin fragment 1-5 (Tyr-Pro-[3H]Phe-Pro-Gly), a specific substrate for DPP IV, in renal brush-border membrane vesicles isolated from DPP IV-positive and DPP IV-negative rats. Although the membrane vesicles from DPP IV-positive rats were able to hydrolyze the pentapeptide to di- and tripeptides with the subsequent active transport of these products via the H+ gradient-dependent peptide transport system, the membrane vesicles from DPP IV-negative rats failed to hydrolyze the pentapeptide and hence lacked the ability to transport the radiolabel actively from the parent peptide. The H+ gradient-dependent glycyl-sarcosine uptake and the Na+ gradient-dependent proline uptake, however, were normal in DPP IV-negative rats. Urine analysis revealed that the DPP IV-negative rats excreted proline- and hydroxyproline-containing peptides in significantly increased amounts in their urine compared with control rats. Furthermore, following intravenous administration of Tyr-Pro-Phe-Pro-NH2, a peptide that is exclusively hydrolyzed by DPP IV, urinary excretion of the peptide in the intact form was many-fold greater in DPP IV-negative rats than in control rats. These data provide conclusive evidence for the obligatory role of DPP IV in the renal handling of proline (and hydroxyproline)-containing peptides.

PMID: 1967253 [PubMed - indexed for MEDLINE]


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