Enzyme Kenetics
velocity
One way to inhibit an enzyme is by changing pH, which varies protonation/deprotonation on an enzyme. Describe the relationship between pH and pKa that will be closest to Vmax
pH < pKa, enzyme will be protonated
pH > pKa, enzyme will be deprotonated
with Two sites (one needing protonation and the other deprotonation):
pKa(deprotonation) < pH < pKa(protonation)
What is the building block of lipids?
Draw 18:2(delta9,12,15)
Fatty acids
(Picture on laptop, uploading images costs money)
This type of messenger molecule is a lipid
Steroid hormones
1) What can diffuse across a cell membrane unassisted?
2) Carriers and transporter allow ______ to pass through. Is this active or passive transport?
3) How are channels and pumps different?
1) uncharged molecules
2) ions. either active or passive **note! uniporters are 1-direction, Contransports: symporters have two ions in the same direction at once and antiporters have two ions in opposite directions**
3) channels have only one gate while pumps have two. Both are selective, but pumps are more so.
(Please also describe what the answer means in general)
V0, this is the rate of the reaction under the conditions of [S]
Describe irreversible inhibition
What kind of lipid is used on storage? Draw it!
(feel free to use Rx to represent fatty acid chains)
Triacylglycerols! (check image)
Which 4 vitamins are fat-soluble
A, D, E, K
Contrast ordered and disordered lipid phases and relate these states to membrane behavior.
Liquid-ordered: mostly saturated fatty acids.
Liquid-disordered: mostly unsaturated fatty acids
cholesterol INCREASES membrane fluidity when it's around saturated fatty acids (disrupts packing), and DECREASES membrane fluidity when it's around unsaturated fatty acids.
Upon inverting the Michaelis-Menton Equation, You get the Lineweaver-Burk plot equation, which is linear with the form y = mx + b. Please describe what these variables tell you and where you'd find them on a graph.
b = 1/Vmax. This is the y-intercept and tells you Vmax
m = Km/Vmax. This is the slope of the line
X is proportional to the concentration of substrate.
NOT ALL ENZYMES FIT MICHAELIS-MENTEN KINETICS. I don't have a question about this I just thought we could all use a reminder.
Describe competitive inhibition and the related kintetics
Substrate/Inhibitor compete for same active spot on enzyme.
Vmax is unchanged, Km -> aKm (apparent Km)
(SLOPE changes, x-intercept is constant)
Draw a glycerophospholipid.
Where is this used? How is it different from a sphingolipid?
Check image, it's structural in membranes.
Glycerophospholipids have 2 fatty acid chains bound by ether linkages. Phosphate group also on glycerol backbone via ether.
Sphingolipids have a nitrogen linking the sphingosine backbone to the fatty acid.
Both have headgroup. Glicero- and sphingo- can be (but are not necessarily) -phospholipids based on that headgroup.
This molecule is based on a glycerophospholipid, where the phosphate group is bound to a sugar. The OH groups on this sugars can be phosporolated in the 3, 4, or 5 positions by ______ or dephosphorolated by _______. It acts as a messenger and regulates structure/metabolism
Phosphatidylinostol;
Phosphorolated by PI-Kinases and Dephosphorolated by PI-Phosphatase
What are the type of diffusion across a lipid bilayer? Which enzymes facilitate that?
Transverse and lateral diffusion
Transverse diffusive enzymes:
Flipases: outer -> inner membrane (uses ATP)
Floppases: Inner -> outer membrane (Uses ATP)
Scramblases: High -> low concentration (No ATP, some use Ca+)
DescribeUncompetitive competition and the related kinetics
Inhibitor binds to ES complex
Vmax decreases, Km decreases
(Vmax/a') (Km/a')
Draw a Sterol structure! What are these used in?
(Draw the three specific ones we were supposed to know. A clue {but not the image} will be on the answer so you'll have another chance if you don't remember)
[Image]. Hormones/signaling molecules. Cholesterol, Testosterone, and Beta-estradiol
These enzymes remove and add phosphate groups to phosphoatidylinositol
PI-Kinases and PI-Phosphates
Types of membrane proteins.
Steps to Snap Receptor (SNARE) protein funciton
Integral, pheripheral, lipid-linked
1. v-snare and t-snare bind and zip together
2. zipping creates tension, favoring hemifusion - membranes come into contact
3. Complete fusion creates fusion pore
4. Pore widens, vesicle contents release
List the five key structural features of chymotrypsin and explain the role of each.
***Bonus Jeopardy***
I found 3 Nobel Prizes this semester. Who won them for what reason in what year?
Check notes, it's 7:25 on thursday and I saw this on the study guide and panicked
****************
Cholesterol Trafficking; Brown & Goldstein, 1985
First Membrane Protein Structure; Deisenhafer, Huber, & Michel, 1988
Membrane Trafficking Regulation via Vesicles; Rotham, Schekman, & Sudhof, 2013
Describe Noncompetitive Inhibition and kinetics
Allosteric effect: Enzyme no longer stabilizes transition state.
Km does not change, Vmax does
The simplest sphingolipid is a __________. _______ Is a type of sphingolipid with one or more sugars attached as the head group, and it can be a _____, a _______, or, wit certain acids attached, a ________.
Ceramide.
Glycosphingolipid, cerebroside (single sugar), globoside (multiple sugar), or a ganglioside
Lipids can be Extracted using ________.
Two phases are created. The first (top) layer contains water, methanol, proteins, and sugars. The second (bottom) layer contains lipids and ______.
Chromatography, chloroform
1. BAR domains
2. The _____________ describes how both chemical composition and charge are relevant to transport across the cell membrane
1. Induce curvature
2. Electrochemical gradient