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Good day everybody. I am a new graduate student at my university and I'm studying the inhibitory effect of compounds on these enzymes. The problem I am having is that when I do the activity assays for the CYP enzymes, the "jump" between my negative control (no CYP activity) and positive control(100% CYP activity) isn't big enough. I've done this assay several times and can't figure out what is wrong. I know enzymes are delicate little things and need the right conditions to be fully active, mainly temperature and pH. But as far as I know, I maintain these two factors while doing the assay. I also know that repeated freezing and thawing of the enzyme will denature it and it will lose activity little by little, but my "trainer" had aliquoted small volumes into microcentrifuge tubes and I have used several of these (3 or 4 so far) and get the same result no matter if it was the first time using that tube or not. My "trainer" also did the assay herself and gave me some tips and I try to follow everything she did. She got a nice difference between her positive and negative when she did it.

So I'm thinking it is my technique. My trainer said I only need to practice, which I have no problem with but I don't want to keep practicing the wrong thing. Can anyone tell me any bad technique skills would cause enzyme activity to drop?

Which drug induce cytochrome P450 (CYP) after single-dosing in human ?

do mice liver express Cytochrome P450 1A1 enzyme after the exposure of Benzo(a)pyrene and Di-methylbenzanthracene

Clopidogrel is often used to keep coronary stents patent

Clopidogrel resistance can be up to 30% of African/Asian populations

Should we be doing more routine testing for the marker of resistance- CYP 19 in these populations? Otherwise we may be giving placebo to our stent patients...

Any advice on Cytochromes P450 (CYP) panel on chemotherapy? What's your gene list? Clinically, Roche got an FDA-approved panel but is outdated and limited - do you have an updated list?

Cytochromes P450 (CYP) are a major source of variability in drug pharmacokinetics and response. Of 57 putatively functional human CYPs only about a dozen enzymes, belonging to the CYP1, 2, and 3 families, are responsible for the biotransformation of most foreign substances including 70–80% of all drugs in clinical use. The highest expressed forms in liver are CYPs 3A4, 2C9, 2C8, 2E1, and 1A2, while 2A6, 2D6, 2B6, 2C19 and 3A5 are less abundant and CYPs 2J2, 1A1, and 1B1 are mainly expressed extrahepatically.http://www.sciencedirect.com/science/article/pii/S0163725813000065

Hi all, I'll try and explain this as easy as I can. I have undergone a short project to calculate cyp3a4 half life after mRNA suppression. The first stage of this was to calculate change in gene expression of siRNA transfected hepatocytes compared to untreated through qPCR and pffafl analysis. Three incubation periods were used, 48, 72 and 96h for all samples. There was decrease in gene expression from 48 to 72h (around 50%), however gene expression increased in 96h back to similar level at 48h. This was part of my honours project, hence I have little experience understanding experimental data. Can anybody explain why this may be occurring? Many thanks for helping.

We have shown that the presence of CYP enzymes (CYP 1A1, 2A6) in exosomes derived from cervical cancer cells (Ca Ski Cells). When we treated these exosomes to HIV-1 infected U1 macrophages, we observed a massive increase in HIV replication. We think the increase in the viral replication is occurring via a CYP-mediated oxidative stress pathway. If we could inhibit the specific CYP enzymes within the exosomes, it could clarify their role. I am curious if anyone has ideas about ways to inhibit CYPs within exosomes?

Currently we are planning qPCR gene expression studies of the biotransformation system of our hepatocyte-derived cell line from cattle.

What would be suitable CYP inducers beside beta-naphtoflavon for CYP1A1 and dexamethasone for CYP3A?. Is there any possibilty to induce phase II biotransformation enzymes like UGT1? What CYPs and phase II enzymes are espacially important in cattle and should be definitly attested?

Thank you for your help.

Hi all, i'll try and keep this short as i can. i have been undertaking an honours project for the past 5 weeks about determining cyp3a4 degradration via mRNA suppression. I have derived a half life value but i want to know how this value and those mentioned previously in literature regarding cyp3a4 can be important for patients as a predictor of drug-drug interactions and clinically. Many thanks for helping.