Inhibition of proximal tubular hydrolysis and reabsorption of bradykinin by peptides

[3H] bradykinin ([3H] BKN) was microinfused alone or in the presence of a 390- or 780-fold excess of BKN or angiotensin I (AI) into proximal tubules in Inactin-anesthetized rats. Urinary excretion of 3H-labeled material was measured, and intact peptide and its metabolites were identified and quantified. When [3H] BKN was administered with BKN or AI, urinary recovery of 3H-labeled material was increased in a manner directly proportional to tubular length, suggesting that reabsorption of [3H] BKN is related to extent of tubular contact. BKN and AI were equally effective in inhibiting the reabosroption of [3H] BKN and its metabolites from proximal tubular fluid. In contrast, BKN but not AI effectively inhibited the enzymatic hydrolysis of [3H] BKN in the proximal tubule, The data suggest that the proximal tubular mechanism for reabsorbing BKN and its metabolites is of high capacity but not high specificity and that the mechanisms for enzymatic cleavage and reabsorption of BKN and its metabolites may had different specificites and capacities.

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Micropuncture evidence of rapid hydrolysis of bradykinin by rat proximal tubule

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.230.5.1420 ◽

1976 ◽

Vol 230 (5) ◽

pp. 1420-1424 ◽

Cited By ~ 63

Author(s):

FA Carone ◽

TN Pullman ◽

S Oparil ◽

S Nakamura

Keyword(s):

Peptide Mapping ◽

Proximal Tubules ◽

Urinary Recovery ◽

Transit Times ◽

Proximal Tubular ◽

Distal Tubules ◽

Rapid Hydrolysis ◽

Hydrolysis Of ◽

Higher Doses ◽

Rat Proximal Tubule

3H-labeled bradykinin ([3H]BKN) and 14C-labeled inulin ([14C]In) were simultaneously microinfused into proximal or distal tubules in Inactin-anesthetized rats, and urinary excretion and tubular transit times were measured. In other experiments higher doses of [3H]BKN were microinfused and intact peptide and its metabolites identified and quantified by two-dimensional peptide mapping. The site of infusion was identified by neoprene injection and microdissection. Urinary recovery of 3H label was 24.1% when proximal tubules were infused and 98.0% when distal tubules were infused. For proximal tubules, 85% of 3H activity recovered from urine consisted of metabolites (81%[3H]Pro and 4% [3H]Arg1-Phe5) and 15% was intact BKN. Urinary recoveries of [3H]BKN and metabolites were unrelated to tubular length. With distal tubules all 3H activity appeared as intact BKN. Excretion curves of simultaneously infused [3H]BKN and [14C]In showed no marked differences in configuration for either proximal or distal or distal tubules. We suggested that removal of [3H]BKN by proximal tubular cells occurs by rapid enzymatic cleavage at the luminal surface with reabsorption of most of the products and excretion of the remainder.

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Effects of constituent amino acids on tubular handling of microinfused angiotensin II

AJP Renal Physiology ◽

10.1152/ajprenal.1978.234.4.f325 ◽

1978 ◽

Vol 234 (4) ◽

pp. F325-F331 ◽

Cited By ~ 1

Author(s):

T. N. Pullman ◽

F. A. Carone ◽

S. Oparil ◽

S. Nakamura

Keyword(s):

Amino Acids ◽

Angiotensin Ii ◽

Aspartic Acid ◽

Free Amino ◽

Renal Tubules ◽

Urinary Recovery ◽

Proximal Tubular ◽

Distal Tubules ◽

Proximal Convolution ◽

Hydrolysis Of

[14C]angiotensin II ([14C]AII) was microinjected alone or with excess L-isoleucine (IIe) or L-aspartic acid (Asp) into renal tubules of anesthetized rats. Urinary excretion of 14C-labeled material was measured, and the intact peptide and its metabolites were identified and quantified. When isoleucine was administered with [14C]AII, urinary recovery of the 14C-labeled material increased directly with distance of infusion site from glomerulus, and most of the radioactivity in urine was [14C]Ile. The data suggest that isoleucine interfered with reabsorption of [14C]Ile derived from hydrolysis of [14C]AII and less so with the hydrolysis itself. When aspartic acid was administered with [14C]AII into the proximal 5/6 of the proximal convolution, total urinary recovery of the 14C-labeled material was unchanged, but percentage of recovery as [14C]AII increased; with infusion into the distal 1/6 of the proximal convolution, total urinary recovery of the 14C labele increased. The data suggest that aspartic acid interfered with the enzymatic hydrolysis of [14C]AII and reabsorption of isoleucine. In distal tubules the 14C label was almost completely recovered as intact [14C]AII in all protocols. The results show that free amino acids influence proximal tubular handling of small linear peptides in rats.

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Enzymatic Hydrolysis of Carotenoid Fatty Acid Esters of Red Pepper (Capsicum annuum L.) by a Lipase from Candida rugosa

Zeitschrift für Naturforschung C ◽

10.1515/znc-2000-11-1220 ◽

2000 ◽

Vol 55 (11-12) ◽

pp. 971-975 ◽

Cited By ~ 16

Author(s):

Dietmar Ernst Breithaupt

Keyword(s):

Enzymatic Hydrolysis ◽

Candida Rugosa ◽

Fatty Acid Esters ◽

Red Pepper ◽

Free Form ◽

Enzymatic Cleavage ◽

Reaction Conditions ◽

First Time ◽

Hydrolysis Of ◽

Acid Esters

Analyses of red pepper extracts which had been pretreated with lipase type VII (EC 3.1.1.3.) from Candida rugosa showed for the first time pepper carotenoid esters to be substrates of this enzyme. However, the extent of enzymatic hydrolysis depends on the respective carotenoid and was not quantitative compared to chemical saponification. After enzymatic cleavage, 67-89% of total capsanthin, 61-65% of total zeaxanthin, 70-81% of total β-cryptoxanthin and 70-86% of total violaxanthin were detected in free form. Nevertheless, the method described here offers the possibility to cleave in part several carotenoid esters originating from red pepper quickly and under comparatively mild reaction conditions. Replacement of the generally performed alkaline hydrolysis by enzymatic cleavage allows the resulting product to be used in food industry as “natural” coloring agent e.g. to colour cheese and jellies.

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Tubular handling of neurotensin in the rat kidney as studied by micropuncture and HPLC

AJP Renal Physiology ◽

10.1152/ajprenal.1989.256.1.f100 ◽

1989 ◽

Vol 256 (1) ◽

pp. F100-F106

Author(s):

T. Bjerke ◽

E. I. Christensen ◽

N. Boye

Keyword(s):

High Performance ◽

Rat Kidney ◽

Proximal Tubules ◽

Urinary Recovery ◽

Rat Serum ◽

Proximal Tubular ◽

Distal Tubules ◽

Extensive Degradation ◽

Convoluted Tubules

Micropuncture studies were performed to assess the reabsorption and metabolism of the vasoactive peptide neurotensin (NT) in individual nephron segments and compare it to the handling of the closely related peptide bradykinin (BK). Rat proximal and distal convoluted tubules were microinfused with [3H]NT or [3H]BK. In a second set of experiments, [3H]NT and its metabolites in the ureteral urine were separated and characterized using high-performance liquid chromatography (HPLC) technique. The urinary recovery of 3H-labeled material was 31% when proximal tubules were microinfused with [3H]NT and 94% when distal tubules were infused. For proximal tubules the label recovered in the ureteral urine consisted exclusively of metabolites of NT and appeared as tyrosine, NT1-11, probably NT9-13, and two uncharacterized products. For distal tubules, 9% chromatographed as intact NT in the urine and except for the proportion the metabolites were almost identical to those found when proximal tubules were microinfused. Following microinfusion of [3H]BK into proximal tubules, the urinary recovery of 3H-labeled material was 19%. There was no correlation between fractional reabsorption of 3H-labeled material and proximal tubular length when [3H]NT or [3H]BK was microinfused. In vitro incubation studies with rat ureteral urine showed extensive degradation of NT yielding tyrosine, NT1-6, probably NT9-13, NT, and two uncharacterized products. In contrast, there was no detectable breakdown of BK over a 32-min period. Finally, [3H]NT was incubated in rat serum, and these experiments also showed degradation of the peptide but not to the extent as when incubated in ureteral urine.(ABSTRACT TRUNCATED AT 250 WORDS)

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Angiotensin I-converting enzyme inhibitory activity and antioxidant capacity of bioactive peptides derived from enzymatic hydrolysis of buffalo milk proteins

International Dairy Journal ◽

10.1016/j.idairyj.2016.11.006 ◽

2017 ◽

Vol 66 ◽

pp. 91-98 ◽

Cited By ~ 46

Author(s):

Mahmoud Abdel-Hamid ◽

Jeanette Otte ◽

Cristian De Gobba ◽

Ali Osman ◽

Essam Hamad

Keyword(s):

Enzymatic Hydrolysis ◽

Antioxidant Capacity ◽

Inhibitory Activity ◽

Bioactive Peptides ◽

Milk Proteins ◽

Buffalo Milk ◽

Converting Enzyme ◽

Angiotensin I ◽

Angiotensin I Converting Enzyme ◽

Hydrolysis Of

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PREPARATION AND USE OF ENZYMATIC MATERIAL FROM P. LILACINUM TO YIELD CLINICAL DEXTRAN

Canadian Journal of Microbiology ◽

10.1139/m57-028 ◽

1957 ◽

Vol 3 (2) ◽

pp. 239-247 ◽

Cited By ~ 9

Author(s):

Arthur F. Charles ◽

Leone N. Farrell

Keyword(s):

Enzymatic Hydrolysis ◽

Enzyme Production ◽

Enzyme System ◽

Fermentation Broth ◽

Extracellular Enzyme ◽

Clinical Use ◽

Enzymatic Cleavage ◽

Optimum Yield ◽

Fermentation Broths ◽

Hydrolysis Of

The development of a method for preparing and standardizing extracellular enzyme from strains of Penicillium lilacinum has permitted the degradation of native dextran in such a way that clinical dextran could be separated in reasonable amounts. This enzyme system has been used regularly on crude fermentation broths as well as native dextran. The enzyme system was found to withstand heating at 60 °C. for 30 min. within the range pH 6.0 to 8.5. At pH 5.0 activity was almost completely arrested by heating at 60 °C. At 23 °C. activity was greatest at pH 5.0 to 6.5. It was found to be more labile to acid than to alkali, becoming inactivated at pH 3.0. The optimum medium for enzyme production contained 2% native dextran and 2% corn steep solids. Optimum yield of clinical dextran (50–65% recovery) was obtained when the hydrolysis of the fermentation broth was arrested at ηr 2.4. The yield was increased by a second enzymatic hydrolysis of partially degraded dextran which had heretofore not been recoverable for clinical use. The clinical dextran prepared by enzymatic cleavage has complied with the regulations of the Food and Drug Directorate and has been used clinically.

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