Biochemistry Flashcards
Regulation of Citrate Syntase
Positive Regulation By Citrate
Regulation of Isocitrate Dehydrogenase
Positive by ADP and Ca2+
Negative by NADH
Regulation of a-ketoglutarate Dehydrogenase
Positive by Ca2+
Negative by NADH
Regulation of Malate Dehydrogenase
Negative by NADH
What are precursors of Acetyl-CoA
Glucose (via pyruvate) Alanine (via Pyruvate) Ethanol Ketone body (Acetate) Fatty Acid (Palmitate)
Why isn’t oxaloacetate a regulator?
The equilibrium between oxaloacetate and malate favors malate so at any time there is only a small amount of oxaloacetate available
How is PDH inhibited?
PDC Kinase phosphorylates a serine residue on E1 in response to Acetyl Coa, and NADH
PDC Phosphotase hydrolyses this phosphate to activate it in response to ADP and pyruvate and Calcium
What TCA cycle intermediates are used in biosynthesis
Citrate - Fatty Acid Synthesis a-Ketoglutarate - AA synthesis, GABA Succinyl CoA - Heme Malate - Gluconeogenesis Oxaloacetate - AA synthesis
What does pyruvate carboxylase do?
Catalyzes addition of CO2 to Pyruvate to make oxaloacetate in anapleurotic reaction
Requires biotin, activated by acetyl-coa
What is E1
Pyruvate Carboxylase
Requires TPP
Carboxylates Pyruvate to form covalent intermediate
What is E2
Transacylase
Requires Lipoic Acid (SS bond)
Grabs acyl group and transfers it onto CoASH, Subsequently reduces FAD on E3
What is E3
Dihydrolipoyl Dehydrogenase
Requires FAD and NAD
FAD is reduced to FADH2 and subsequently reduces NAD to NADH
What is riboflavin a precursor to?
Vitamin B3
Precursor to FAD and FMN
What is Niacin?
Precursor to NAD
What is Thiamine?
Vitamin B1
Necessary for TPP
Can easily become deficient in alcoholics and the malnourished
What is pantothenic acid?
Precursor to CoA
Widely distributed in foods
What regulates Hexokinase?
Glucose 6 P
What regulates PFK-1
F26BP, AMP are positive
H+, Citrate, and ATP are negative
What conditions cause lactic acidosis
Circulatory insufficiency Anemia Mitochondrial enzyme defects Poisons Cancer Ethanol Intoxication Hepatic Failure
What transporters don’t exist
oxaloacetate
NAD/NADH
AcCoA
What carriers do exist?
Malate Aspartate Glutamate Pyruvate A-Ketoglutarate
Where is the glycerol phosphate shuttle?
Most tissues
Where is the malate aspartate shuttle?
Mainly liver, kidney, and heart
What is the malate aspartate shuttle?
Requires transaminase reaction of aspartate to aketoglutarate and oxaloacetate to malate
Oxaloacetate reduced to malate in cytosol which is transported and reduces NAD in the IMM to NADH for the ETC
Oxaloacetate inside is transaminated to aspartate which is shuttled out and transaminated back to oxaloacetate
Transamination also converts glutamate ot akg on inside and back outside
