Biochemistry and Molecular Biology

An enzyme in the native buffer solution exists in the equilibrium, native (N) state <--> denatured (D) state. So it has its KM and Vmax in this buffer. If one adds a cosolute to the enzyme solution, and if the cosolute shifts the equilibrium from D state to N state (i.e., the enzyme gets stabilized), then will the cosolute also effect the KM and Vmax?

My first post so please bear with me if my question is a bit unclear. My professor was lecturing about enzyme kinetics and I am a little unclear about the meaning of Km. Specifically, Km is supposed to measure how effectively the enzyme binds to substrate and is defined: km = ((K-1)+(K2)) / (K1) Where K-1 is the rate of the reverse reaction: ES--> E+S, K2 is the rate of the product forming reaction: ES-->P, and K1 is the rate forward reaction: E+S-->ES My question: is K2 dependent on K-1 and K1 or independent? If independent, it would seem that if K1 was very large (good enzyme-substrate binding), and K-1 small, K2 could either be very larg…

I'm having a spot of bother with a monooxygenase assay for a certain mosquito larvae. When i add the hydrogen peroxide the colour change is almost immediate, but it starts to fade after a while, and the colour is pretty much gone by the time i'm meant to read the plate. This is what i've been doing: 20ul of homogenate in duplicate 80ul of 0.1g 3,3',5,5' Tetramethyl Benzidine (crusher) dissolved with 5ml methanol, plus 15ml of 0.25M sodium acetae buffer pH 5.0 to each well. 25ul of 3% hygrogen peroxide to each well Read at 1 and 2hrs at 650nm endpoint. I've repeatedly checked my buffer pH's and made sure the mixtures in each well are all stirred up. Any …

Hey everyone, I'm interested in proteins, sugars and lipids on the surface or red blood cells. Does anyone know where (or if) one can purchase glycophorins for example, or other surface molecules? I really hope someone can give me some input on this matter! Thanks a billion!

I wonder how much it would cost, approximately, to set up an own "hobby lab" for genetic engineering? Of course I'm not aiming for high-end stuff, but good enough for constructing simple recombinant DNA & insert it into a living cell, perform microinjections, etc. A suitable microinjection-kit seems to be way cheaper than I imagined. I figured it would cost around $15000-$20000 atleast, but for $1500-$2000 you can get quite good things, specially when considering second hand apparatus. Though micropipette pullers are quite expensive, but I've seen a few cheap ones on labx.com. Perhaps you can make them by yourself, trial & error with a burner and glass pipette…

Hey, I have some multiple choice questions that's bother me. I'll try translating them hoping someone could give me an answear. 1. Hydrophobic interaction in protein is giving important stabilization contributions a) to proteins secundary- and tertiarystructure. b) just to the orientation of polar amino acids c) to the proteins primarystructure d) after every possible hydrogenbonding are formed e) only in hydrophobic fases I am here guessing a or d, but I am very uncertain. 2. The structural membraneproteins are characterized in case of that they a) don't transport small molecules b) exist only by beta sheets c) show prostetic carbohydrate groups o…

Hopefully this is a quickie for someone who knows more about bio than I do. PBP2, which is a membrane-bound protein in methicillin-resistant Staphylococcus aureus (MRSA) and other bacteria catalyzes linking of peptidoglycans. Which side of the cell membrane/wall does the exposed part of the protein reside on (cytoplasm, or outside)? The diagrams don't say and my background is not in biology. The paper I'm looking at is here: http://www.sciencemag.org/cgi/content/full/315/5817/1402 Thanks for your help.

I believe there are only a few hundred complete sequenced genomes. I realize you mainly sequence the genome of an organism that is heavily involved in research, eg. model organisms such as E.coli, yeast, etc. But my question is this: If I discover a new bacterium tmrw, what would be the time and cost to sequence its genome? (obviously will vary with equipment, but please give approx guidelines) Thanks!

In humans, the urge to breathe result from high concentration of O2 in the blood; there are no direct physiological sensors of blood pO2. Skindivers often hyperventilate (breathe rapidly and deeply for several minutes) just before making a dive in the belief that this will increase the O2 content in their blood. a. Does it do so? b. Use your knowledge of hemoglobin function and the Bohr effect to evaluate whether this practis is useful.

I'm trying to do my biology AS coursework and I was wondering: Is there a way to quantify the relative strengths (by strength I mean how reducing they are...i.e. how fast and how much they reduce) of reducing sugars (specifically glucose, fructose and maltose)? If so what is it?

I need help w/ a question: Insulin protein has 2 polypeptides A and B. Human and duck insulins have the same sequence except for six below. Is the pI of human insulin higher or lower than duck insulin? AA seq. A8 A9 A10 B1 B2 B27 Human Thr Ser Ile Phe Val Thr Duck Glu Asn Pro Ala Ala Ser

I understand the definition of this phenomnen is that restriction enzyme eats up sequences which it is not designed to chew up. But, I am very curious to know why they coined it as "STAR" activity. anything on this would be appreciated. babA

Hello !! I am wondering about the electrochemical gradient and the proton pumps in mitochondria - Complexes I, III and IV, how is it created? Protons move from the matrix to the intermembrane space but how is this coupled with electron movement along the chain? Is it because the outer side of the membrane gets negatively charged and that's the driving force for proton movement or is it a confomational change in these complexes that displaces the protons... Many thanks !!!

Cells exposed to a hypotonic solution can take in more water than is expelled, thereby expanding and exploding. It is said that a cell has lysed (sp?) when this occurs. My girlfriend and I were discussing something and this term came up ... but neither of us could remember the term that refers to when a cell shrivels up, as with a cell exposed to a hypertonic solution! Note - I'm not assuming that all cells do this, regardless of cell walls (as in plants) and such, or anything of the sort - really, I'm just curious about the term for cellular implosion. I think there is a term ... and so does my girlfriend. Neither of us can remember it, though, and my googling is…

I did a lab on enzymes and while trying to do the Lab write up, i'm not sure how to answer most of the questions, so i'm assuming that I didn't really understand the purpose of the lab. In the first part we were supposed to analyze the dependence of the enzyme activity on the enzyme concentration. We had 6 test tubes with KOH and another with a sodium acetate buffer, water, and acid phosphotase, heated it, and then added PNPP (which initiates a phosphotase reaction). Then this was added to a test tube with KOH to stop the reaction, and after intrevals of time (0-15 minutes), a certain amount was taken from the previous reaction mixture and added to the next test tub…

Hi, I've read a bunch of papers on transmembrane transporters (citrate, lactate, etc) and many papers use a LiCl stop buffer to "stop" transport but do not say why LiCl stops transfer. What is the mechanism of action? Thanks.

Hi everyone, Protein structure is a complex thing...and also confusing! I was going through literature about protein structure prediction. If given a primary sequence of a protein, how can secondary structure be reliably predicted? I am aware of tendency of aa to be associated with different secondary structures, is there a specific algorithm used for calculation of secondary structure? Is there any other way to model a protein structure based on primary sequence besides homology modelling? Thanks in advance for input and also for reading this!

Is the digestion of protein the stomach by pepsin directly importnt for protein breakdown per se or is there another purpose or benefit in the production of gastric amino acids and peptides?

hey.. i was wondering.. since Fibrodysplasia Ossificans Progressiva causes the muscle, ligaments, and tendon tissue to turn into bone tissue.. could their possibly be a reverse of it? that causes the bones to turn into soft tissues? id like the name of it if there is a documented disorder like this. could they also use genes from someone with that disorder as a treatment for someone with FOP?

A DNA molecule containing multiple identical repeats and a single unique sequence was examined by C0t analysis. 10% of the DNA had an observed C0t1/2 value of 2 x 10-3 mol.l-1.s and the remaining 90% an observed C0t1/2 value of 8 x 10-3 mol.l-1.s. What fraction of the total DNA is contained in one repeat? How do I figure tis out? its multiple choice out of a. 0.25% b. 2.5% c. 4% d. 10% e. 90%

Hi everyone, I'd be really grateful if anyone could answer this....I was assuming that it was the flow of electrons that the body somehow manages to break down (as in a flow of electrons being a electrical charge). My lecturer didn't seem to know, my text books don't go into it, and neither does wikipedia etc....does anybody know? thanks in advance! Gav

I'm considering a career in virology, a subject that has always held special interest to me. I was hoping that someone might be in this field, and could give some feedback (i.e. like/dislike, pay, aspects, et.) also, i am interested in a lesser degree to the military, is there any way the two could be merged?

Hi! I cant do this question!... can any1 help? Discuss why how the henderson-hasselbalch equation indicates that B (buffer capacity) is maximal when the pH equals the pKa? B=dm/d(pH)

Hello, everybody! I´d like to ask a question about collagen (particularly type IV). Does anybody know of a molecule (simple or complex) that attaches preferentially to this protein? I'm trying to target several drugs to collagen type IV and found nothing in the literature. Any thoughts? Hope it isn't a dum question Thanks

Question from an old exam, (studying for the final) can't figure out the answer: "Given that pyruvate can be converted to Acetyl CoA using reactions we learned in this class, write a balanced reaction scheme for converting pyruvate to Alpha Ketoglutarate WITHOUT depleting any TCA Cycle components." any ideas?