Investigation of neutral endopeptidases (EC 3.4.24.11) and of neutral proteinases (EC 3.4.24.4) using a new sensitive two‐stage enzymatic reaction

Indig, Fred E.; Ben-Meir, Daniella; Spungin, Anya; Blumberg, Shmaryahu

doi:10.1016/0014-5793(89)81098-1

Cited by 43 publications

(14 citation statements)

References 23 publications

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“…This indicates the disruption of FITC‐Casein by thermolysin activity and thus a loss of fluorescence quenching. The positive control containing phosphoramidon, the chemical inhibitor of thermolysin, does not show any fluorescence [51]. In addition, no fluorescence signal was detected with IMPI‐GST in buffered solution or IMPI‐GST in the final formulation, indicating the inhibition of thermolysin by IMPI‐GST.…”

Section: Resultsmentioning

confidence: 95%

Development of an insect metalloproteinase inhibitor drug carrier system for application in chronic wound infections

Eisenhardt

Dobler

Schlupp

et al. 2015

Journal of Pharmacy and Pharmacology

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Section: Resultsmentioning

confidence: 95%

Development of an insect metalloproteinase inhibitor drug carrier system for application in chronic wound infections

Eisenhardt

Dobler

Schlupp

et al. 2015

Journal of Pharmacy and Pharmacology

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“…An increase in absorbance at 405 nm was followed for 60 min and ⌬E/min determined from the linear part of the curve. Neprilysin activity was determined as described (22), but with Suc-Ala-Ala-Phe-pNA as substrate (23). To cleave the resulting Phe-pNA 5 l of 0.5 mg/ml membrane alanine AP (Sigma) was included in the test, which had been shown earlier to be well above the expected activity of neprilysin.…”

Section: Methodsmentioning

confidence: 99%

Human Adipose Tissue Cells Keep Tight Control on the Angiotensin II Levels in Their Vicinity

Schling¹,

Schäfer²

2002

Journal of Biological Chemistry

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Human adipose tissue expresses all components necessary for the local production of angiotensin II, which has multiple functions in adipose tissue, ranging from regulation of local blood flow to complex influences on tissue homeostasis. Still the mechanisms controlling human adipose tissue angiotensin II concentrations are not yet known. We investigated whether angiotensin II is degraded by human primary cultured preadipocytes and adipocytes and which enzymes are responsible for its metabolism. Distinct but transient angiotensin II production was limited by degradation due to consecutive proteolytic cleavage by endopeptidase and aminopeptidase activities. The endopeptidase could be identified as neprilysin expressed on the surface of both preadipocytes and adipocytes. Degradation of angiotensin II was preceded by a lag phase that was considerably longer in preadipocytes. This time span could not be explained by an induction of neprilysin nor by an increase in its surface localization. Following the lag phase, adipocytes showed a higher degradation activity than preadipocytes as mirrored by increased neprilysin levels and activity measured in their membrane fractions. Our findings demonstrate that human preadipocytes and adipocytes differentially express functional neprilysin and aminopeptidase activity involved in the regulation of angiotensin II concentrations in human adipose tissue.

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“…We found that endopeptidase activity of spermatozoa is proportional to the number of cells per unit volume and, as such, can serve as a measure of accumulation (unpublished data). An aliquot of 20 Al from each well was transferred into a microtiter plate and assayed for endopeptidase activity as described (11).…”

Section: Methodsmentioning

confidence: 99%

Sperm attraction to a follicular factor(s) correlates with human egg fertilizability.

Ralt

Goldenberg

Fetterolf

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

175

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Spermatozoa normally encounter the egg at the fertilization site (in the Fallopian tube) within 24 hr after ovulation. A considerable fraction of the spermatozoa ejaculated into the female reproductive tract of mammals remains motionless in storage sites until ovulation, when the spermatozoa resume maximal motility and reach the fertilization site within minutes. The nature of the signal for sperm movement is not known, but one possible mechanism is attraction of spermatozoa to a factor(s) released from the egg. We have obtained evidence in favor of such a possibility by showing that human spermatozoa accumulate in follicular fluid in vitro. This accumulation into follicular fluid was higher by 30-260% than that observed with buffer alone and was highly significant (P < 10-8). Not all of the follicular fluids caused sperm accumulation; however, there was a remarkably strong correlation (P < 0.0001) between the ability of follicular fluid from a particular follicle to cause sperm accumulation and the ability of the egg, obtained from the same follicle, to be fertilized. These findings suggest that attraction may be a key event in the fertilization process and may give an insight into the mechanism underlying early egg-sperm communication.Spermatozoa normally meet the egg at the fertilization site (isthmic-ampullary junction of the Fallopian tube) within 24 hr after ovulation (1)(2)(3). In women, cervical spermatozoa have been reported to possess prolonged acrosomal integrity (in vivo), and this has led to the suggestion that the human cervix may serve as a site of sperm storage (4). In cattle, pigs, and rabbits it has been shown that a considerable fraction of the spermatozoa ejaculated into the female reproductive tract remain in the isthmus of the Fallopian tube until ovulation occurs; they then resume their motility and reach the fertilization site of the ampulla within minutes (2). The mechanisms for sperm selection and the synchronization between ovulation and sperm movement in the female reproductive tract are not known. One plausible mechanism for directed sperm movement would be the attraction of mammalian spermatozoa to factor(s) released from the egg. In vivo studies are currently difficult or impossible, and the many techniques available for measuring leukocyte chemotaxis in vitro (5) appear to be inadequate for studies on mammalian sperm chemotaxis, primarily because of the complexity and rapidity of sperm motion, which subsequently results in poor signal-to-noise ratios. On the other hand, microscopic methods have been useful for demonstrating chemoattraction of invertebrate spermatozoa to the egg (6, 7). Such studies in the mammal have not been reported to our knowledge. Here we examine the possibility of sperm attraction to follicular factor(s) by measuring sperm accumulation in follicular fluid in vitro. We show that human spermatozoa indeed accumulate in follicular fluid and that this accumulation correlates with the ability of the egg to be fertilized. MATERIALS AND METHODSPreparations o...

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Investigation of neutral endopeptidases (EC 3.4.24.11) and of neutral proteinases (EC 3.4.24.4) using a new sensitive two‐stage enzymatic reaction

Cited by 43 publications

References 23 publications

Development of an insect metalloproteinase inhibitor drug carrier system for application in chronic wound infections

Development of an insect metalloproteinase inhibitor drug carrier system for application in chronic wound infections

Human Adipose Tissue Cells Keep Tight Control on the Angiotensin II Levels in Their Vicinity

Sperm attraction to a follicular factor(s) correlates with human egg fertilizability.

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