Biology Forum › Molecular Biology › Enzymes
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- August 6, 2012 at 3:36 pm #16734
rk386
ParticipantDo enzymes in the body last permanently, or do they over time get broken down and then replenished/rebuilt/replaced? Also, what controls the amount of enzyme present?
- August 7, 2012 at 3:32 pm #112042
jonmoulton
ParticipantEnzymes are degraded over time. Some are relatively short-lived while others are very persistent, but damage accumulates and they are eventually broken down.
This page might help the system make more sense.
- August 7, 2012 at 10:08 pm #112043
david23
Participantwhat controls the enzyme levels? your genes, and hormonal regulations which again your genes
- August 7, 2012 at 10:16 pm #112045
JackBean
Participantyou seem to put everything under genes, but genes are controlled by many factors as well
- August 8, 2012 at 6:17 pm #112053
rk386
ParticipantThanks. Follow-up question:
Enzymes are degraded over time. Some are relatively short-lived while others are very persistent, but damage accumulates and they are eventually broken down.
Is it known which types of enzymes break down quickly and which are persistent?
- August 8, 2012 at 6:33 pm #112054
JackBean
ParticipantYes, there are soe well-known examples. For those you don’t know about, you can make some predictions.
- August 8, 2012 at 9:47 pm #112057
rk386
ParticipantThanks. If I wanted to look more into this, where would I look?
- August 8, 2012 at 10:03 pm #112058
JackBean
ParticipantThe first choice should be Alberts’ The Cell
- August 8, 2012 at 10:07 pm #112059
rk386
ParticipantOh, great, I have that.
- August 9, 2012 at 3:19 pm #112062
jonmoulton
ParticipantLook for "protein turnover". Here’s an introduction. http://en.wikipedia.org/wiki/Protein_turnover
- August 15, 2012 at 4:04 pm #112095
rk386
ParticipantThanks. Have studies on protein turnover been done for specific proteins, or is it just known in general that that is what happens?
- August 15, 2012 at 4:50 pm #112096
jonmoulton
ParticipantIt has been done for many specific proteins. One good method is pulse-chase analysis. http://en.wikipedia.org/wiki/Pulse-chase_analysis
- August 15, 2012 at 7:03 pm #112097
rk386
ParticipantThanks. It is pretty amazing what technology can do. So by this method, the rate at which a protein breaks down can be determined, e.g. an enzyme?
- August 15, 2012 at 9:21 pm #112098
jonmoulton
ParticipantYes.
- August 17, 2012 at 12:11 pm #112108
KileYe
ParticipantThey will degrade through metabolism
- August 20, 2012 at 3:19 pm #112118
rk386
ParticipantWhat controls that metabolism?
- August 20, 2012 at 3:36 pm #112120
rk386
ParticipantAlso, in terms of the rate at which an enzyme acts, other than substrate concentration and reaction rate, are there any other conditions that would regulate the rate at which an enzyme works? Are there such thing as inherently "slower" or "faster" enzymes?
- August 20, 2012 at 10:37 pm #112121
jonmoulton
Participant"Also, in terms of the rate at which an enzyme acts, other than substrate concentration and reaction rate, are there any other conditions that would regulate the rate at which an enzyme works? Are there such thing as inherently "slower" or "faster" enzymes?"
Oh my goodness yes yes yes. Different protein structures have different rates of catalysis – a single amino acid change can alter or eliminate activity. Temperature and pH affect rate. Many enzymes are controllable by other enzymes — look at allosteric regulation:
http://en.wikipedia.org/wiki/Allosteric - August 21, 2012 at 9:15 pm #112126
JackBean
ParticipantAssuming you mean regulation of rate of one enzyme, then you’re interested in things such as posttranslational regulation (phosphorylation). As jonmoulton mentioned, allosteric regulators are important.
- August 23, 2012 at 1:00 pm #112153
rk386
ParticipantSo there is a difference between the regulation of the rate of one enzyme as compared to the regulation of the rate of many enzymes? How does the regulation of many enzymes work?
- August 23, 2012 at 3:30 pm #112154
JackBean
ParticipantWhat I meant is the regulation of enzyme produced by one gene. On the other hand, as jonmoulton wrote, you can have several genes and the respective proteins will have different amino acids in active side, they may be localized in different compartments etc. But I do not consider this much as regulation, because you must have the gene already, so it’s not really something you can regulate, right?
- August 23, 2012 at 11:10 pm #112157
rk386
ParticipantDo you mean that the same enzyme can be coded for by different genes?
- August 24, 2012 at 2:49 pm #112161
JackBean
ParticipantThat’s exactly what I mean. Actually most of enzymes is in form of isoenzymes coded by several genes.
- August 24, 2012 at 10:26 pm #112164
rk386
ParticipantThanks for explaining.
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