Flashcards in Week 4 Biochem Deck (18):
Collagen is an example of a _____ protein that exhibits a tightly wound _____ structure.
2. Triple helix
Globular proteins are considered highly water soluble because _______.
1. Polar AA Side Chains facing OUT
2. Non-polar side chains interiorly (hydrophobic core)
______ is considered the prosthetic group for Hemoglobin.
Define the structure of Heme:
A porphyrin ring (4 cyclic rings containing nitrogen) with a ferrous (Iron in the 2+ state --> Fe2+) ion in the center.
What 2 forces hold the heme group of myoglobin to its structure?
1. Histidine forms a covalent bond to Fe2+.
2. Hydrophobic Interactions with the porphyrin ring.
What is the importance of the Fe2+ being buried deep inside the porphyrin ring of heme in myoglobin?
It ensures that oxygen only travels through the globular protein and is released as O2, not superoxide.
Sperm whale myoglobin is identical to _______ in humans. But what is different between the two structures and why is it remarkable?
2. The Primary Sequence is very different, but the few CONSERVED amino acids are able to give the same shape and function.
The _____ histidine of hemoglobin is covalently bonded to the heme group, while the ______ histidine is free to act as a buffer for pH and a/b-dimer linkage.
O2 acts as an ALLOSTERIC regulator of its own binding to Hb because binding of one molecule of O2 increases Hb's affinity for more O2 binding.
Describes how Hb responds to changing pH by changing its O2-affinity.
2,3-BPG acts to ______ the O2 affinity of Hb, therefore it is considered to be a ________ of Hb.
2. Negative Allosteric Regulator
4 Allosteric Regulators of Hb:
Titration of a strong acid with a strong base yields __________.
The formation of Salt Water (Salt + H20) at the equivalence point of pH=7.
A ______ Ka implies a stronger acid, while a _____pKa implies a stronger acid ________.
1. Higher Ka = Stronger
2. Lower pKa = Stronger
When titrating a weak acid with a strong base, the pKa is the pH range at which ________.
50% dissociation has occurred
i.e. [HA] = [A-] ....AND....[weak acid] = 1/2[strong base]
The buffer range is seen at ________.
(+/-) 1 pH unit from the pKa
The pKa of Acetic Acid is ________.
pH = 4.75