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May
15
answered Any good website/book to understand protein folding and enzymes?
May
5
comment Proteins that give color (without fluorescence)
Absorption of light does not necessarily give rise to fluorescence, but may give rise to colour if the absorbed light is in the visible region, or to a characteristic absorption spectrum. Flavoproteins are yellow because they absorb light somewhere about 420nm. Fluorescence is the emission of light of a longer wavelength. NADH absorbs light at 340nm. It is also fluorescent, emitting light with a peak at 460nm when excited at 340nm. Phosphorescence is like fluorescence, but light emission persists after the exciting source has been removed.
May
4
comment Proteins that give color (without fluorescence)
Well, flavoproteins are yellow with a characteristic absorption spectrum in the visible region. (The color may depend on redox state). Some copper proteins are blue (ceruloplasmin is an example). Haemoglobin is red!
Apr
30
comment Can we make a rough estimate of the number of generations since the origin of life?
Not an answer to your question, but see here for a most interesting article How many people have ever lived on Earth? by Carl Haub of the Population Reference Bureau. He estimates 106 billion, assuming H.sapiens arose about 50,000 bc, and states Life expectancy at birth probably averaged only about 10 years for most of human history. At the dawn of agriculture (8000 bc), the estimate for world population is 5 million, and 6.5% of all people ever born are alive today.
Apr
28
comment Question regarding an Escherichia coli reaction
The site on an enz where reaction occurs, usually one per subunit, is known as the active site. If both substrates must be present for reaction to occur, this is referred to as a ternary complex, and the reaction may be considered sequential. Another possibility is that the first substrate binds to the enzyme and modifies the enzyme is some way, maybe by covalently attaching an amino group. The 2nd substrate then binds and is modified by the enzyme, maybe by accepting the amino group. Both complexes are binary complexes and the mechanism is referred to as ping-pong
Apr
26
comment How Does NADPH Reduce 1,3-BPG?
For the mechanism of the glyceraldehyde-3-phosphate dehydrogenase reaction see Fersht, Enzyme Structure and Mechanism‌​, pp 469-472. Pages 472-473 may also be of interest.
Apr
26
comment How Does NADPH Reduce 1,3-BPG?
@stygian. It might help if you specified exactly the reaction you are interested in. In both glycolysis and the Calvin cycle is it 3-phosphoglycerate that is produced/consumed in the glyceraldehyde-3-phosphate dehydrogenase reaction. 1,3-diphosphoglycerate is produced/consumed in a separate reaction.
Sep
30
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Sep
12
comment Why do I only breathe out of one nostril?
Does Viagra have any effect?
Aug
21
comment What are the minimal chemical requirements for a food which we all can eat?
Well ... You may have some trouble synthesizing Vitamin B12 by running electricity through a jar of chemicals ... but (as it is a thought experiment) perhaps the famous Miller-Urey experiment is where we should start.
Aug
21
comment Can humans survive without consuming life?
@N0ir As John Lennon put it "Imagine there's no heaven..."
Aug
21
comment Can humans survive without consuming life?
@alex But what about glycogen? Doesn't the breakdown and synthesis of glycogen not require enzymes? And doesn't glycoysis, the TCA cycle and the Respiratory Redox Chain make extensive use of enzymes in turning glucose into "energy"? IMO Chris makes a very good point (to which we may add that no net synthesis of glucose can occur from fatty acids).
Jul
14
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Jun
11
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Jun
11
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Mar
8
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Mar
8
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Feb
7
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Dec
20
awarded  Custodian
Dec
20
reviewed Approve Standard Classification of Disease