Yankton Wyatt
Explain the difference between allosteric enzyme and nonallosteric please.
8:22
Marcos Oliveira
allosteric enzyme has a sigmoidal behavior
8:22
Julie Benjegerdes
are we going to just have to know how to interpret the graph whether it be between different enzymes
or Km or Kcat Dr. Oliveira
8:23
Marcos Oliveira
yes I will work with you all tomorrow
8:24
Rebeca Jimenez
Are we going to be responsible for the Discussion Material listed?
8:24
Marcos Oliveira
not the discussion material
8:24
Teri Randall
Dr. O I had trouble understanding the shift of the graph to the right. I understood all you said I just
cannot figure out how the actual picture of the graph to the shift
8:25
Nkechiamaka Nwosu
Could explain mutagensis?
8:25
Teri Randall
How to see if there is a shift by looking at that graph
8:26
Marcos Oliveira
mutagenesis is an alteration at the genetic level that leads to a change in a amino acid in a protein
structure
8:26
Marcos Oliveira
What graph are we talking about?
Teri Randall
the tissue and lung graph
8:26
8:26
%sat vs pO2
8:27
Marcos Oliveira
I think you are refering to the oxygen binding curve correct
8:27
Teri Randall
yes, sorry
8:27
Marcos Oliveira
I also think you are refering to the hemoglobin oxygen binding curve correct
8:27
Teri Randall
Yes that is it
8:27
Marcos Oliveira
ok the Hb oxygen binding curve changes in response to effectors such as acidic [H+]
8:28
Nathaniel Oyefeso
does the myoglobin curve assume the same shape of the hemoglobin curve?
8:28
Marcos Oliveira
as the environment becomees more cidic the curve shifts to the right
8:28
Mb is hyperbolic Hb is sigmoidal8:29
Teri Randall
Ok, so it's based on the Hb curve
8:29
Marcos Oliveira
ok Hb curve what question do you have?
8:29
Teri Randall
So we should understand if the environment is acidic then the curve shifts to the right which will
increase the %saturation?
8:30
Marcos Oliveira
If the question is acidic yes
8:31
Julliane Swick
no decrease
8:31
Marcos Oliveira
oops correction!!!!
8:31
when the curve shifts to the right due to increase in acidity HB becomes less saturated 8:32
Teri Randall
and Mb becomes more saturated??
8:32
Nathaniel Oyefeso
less
8:32
Marcos Oliveira
Mb does not alter its behavir with changes in environmental acidity
8:33
Karin Dentino
So as H+ concentration increases, and pH drops, the affinity for oxygen decreases and it shifts to the
right? Is that correct? 8:33
Marcos Oliveira
Yes Ms Dentino 8:34
Teri Randall
Thank you
8:34
Nathaniel Oyefeso
what alters the behavior of Mb 8:34
Marcos Oliveira
Mb is not altered by factors that influence Hb
8:34
Nathaniel Oyefeso
thanks 8:35
Adaeze Amuzie
so are there any factors that influence Mb or this is beyound the scope of this class?
8:36
Marcos Oliveira
no Mb is not responsive to any specific facgtor 8:36
Adaeze Amuzie
ok, thanks Dr O :)
8:36
Minh Tran
how would the graph look if BPG binded irreversibly?
8:37
Nkechiamaka Nwosu
in class you mention the acidity might be due to the metabolic activity in the tissues, is the acidity also
caused by the presence of carbon dioxide?
8:37
Marcos Oliveira
the molecule does not bind irreversibly.
8:38
Sonya Valle
So basically it goes toward the direction of acidity?
8:38
Marcos Oliveira
CO2 and metabolic activity contribute to increase in acidic in tissues
8:38
Minh Tran
but if it did? because the hw had a question similar to that
8:38
Marcos Oliveira
ok it BPG were irreversibly bound Hb would be permanently shifted to the right 8:39
Nkechiamaka Nwosu
thanks Dr. O
8:40
Rebeca Jimenez
Are you going to release the answers to the even numbered homework problems?
Marcos Oliveira
even problems will be posted after I finish with chat session
Minh Tran
8:40
8:40
thanks 8:40
Rebeca Jimenez
thanks 8:40
Beth Williams
When you say shifted to the right does that mean that all the oxygen is bound to hemoglobin?
8:40
Marcos Oliveira
no shift to the right mean a less saturated Hb
8:41
Rebeca Jimenez
The entire curve is being shifted to the right, not the concentration of O2
8:43
Beth Williams
Ok...but if you are looking at the graph you showed us in class today, and you look at the hemoglobin
curve, when you look at the curve to the right of the graph it is going up the graph showing that there is
more % saturation...which means there is more O2 bound right? 8:43
Nathaniel Oyefeso
Dr O can you clarify that please? is saturation and concentration the same thing?
8:46
Marcos Oliveira
saturation is % of the Hb sites filled with O2 a number from 0 to 1. 1 meaning sites fully occupied
Rebeca Jimenez
I was refering to the partial pressure of O2.....used the wrong term
8:48
Francess Uzowulu
Okay, so can you now clarify the relationship between pH and saturation please?
8:48
Marcos Oliveira
The lower the pH the lower the saturation based on the changes in oxygen binding curve in response to
changes in [H=} 8:49
Francess Uzowulu
Ohh got it
8:50
Beth Williams
So Rebeca..are you saying that you move the entire curve to the right down the pO2 curve...but how
does that really change what you're looking at? 8:52
Carla Sorbel
Going back to graph about irreversible Hb shifting to the right, that is exactly OPPOSITE of what Anna
told us today, so now I'm throughly confused!!!!8:52
Julie Benjegerdes
Dr. O, I'm sorry, but I still dont understand what more acidity, or more {H+} has to do with saturation of
oxygen 8:52
Rebeca Jimenez
That is the effect of BPG on the curve
8:52
Nathaniel Oyefeso
how does pressure relate to the concentration of oxyigen?
8:53
given two different values of pO2 which one is more saturated? 8:53
Teri Randall
what is irreversible Hb? 8:54
Lilia Esquivel
Wouldn't irreversible Hb shift to the left?
8:54
Francess Uzowulu
Um I think Anna is actually doing a pretty good job tutoring, my notes correspond accordingly (although
I came in for the latter part).. 8:54
Nathaniel Oyefeso
true that
8:54
Francess Uzowulu
She said shifting to left not the right! check your notes again!
8:55
Carla Sorbel
I think she's doing a fantastic job, but I think we're getting left and right mixed up
8:55
Nkechiamaka Nwosu
concentration of oxygenbecause oxygen is a gas it is referred to as partial pressure
8:55
Beth Williams
Ok...so BPG just shifts the curve to the right to make the pO2 further down the graph at a higher partial
pressure?
8:55
Marcos Oliveira
BPG does not change partial pressure the molecule response to changes in partial pressure is altered
pO2 is simply a variable 8:57
Lilia Esquivel
if you have BPG you will release oxygen more freely right?
8:57
Carla Sorbel
That's my point, Anna said to the left and Dr. O is saying to the right.
8:58
Jennifer Ma
BPG just stimulates Hb molecule depicted by the Hb oxygen binding curve to release O2 and therefore,
results in the Hb oxygen binding curve shifting to the right
8:58
Marcos Oliveira
if you have BPG it affects the molecule such that it will become less saturated with o2
8:58
Adaeze Amuzie
Carla, ur getting it all mixed up! Dr O said BPG fixed irreversable not Hb as Anna discussed
9:00
Julie Benjegerdes
so dr. o, when there are more [H+] then it is more acidic which moves the curve to the right meaning
less saturated with oxygen
9:01
Carla Sorbel
Yep, I think that's what I started out saying, I'M CONFUSED!
Marcos Oliveira
yes Julie
Beth Williams
9:02
9:01
On our syllabus it states that we need to read section 5-2 and it covers microtubles and microfilaments
but we haven't covered this in class...is this something we need to understand for the test?
9:02
Teri Randall
Can someone tell me what irreversible Hb is??? 9:02
Adaeze Amuzie
BPG binding and regular Hb binding are different, one shifts to the right (BPG) and the other to the left
9:03
Marcos Oliveira
Ms Williams what I post as reading is for you to read in class we cover essentials the remaining you are
responsible
9:03
Julie Benjegerdes
so dr. o how does more [H+] have to do with more oxygen saturation? is there some kind of binding
thats going on with the H+?
9:04
Beth Williams
ok...thank you!!!
9:04
Marcos Oliveira
relative to normal Hb BPG shifts the standard curve to the right it needs to because standard Hb needs
to be less saturaed with O2 relative to standard 9:04
Nathaniel Oyefeso
what group of acid favor acid catalysis 9:09
Marcos Oliveira
anything capable of donating a proton 9:10
Adaeze Amuzie
@ nathaniel: glu and asp i think (i hope am correct...lol) 9:10
Marcos Oliveira
yep correct
9:12
Nathaniel Oyefeso
k
9:12
Teri Randall
So pretty much all the polar amino acids?
9:12
Lilia Esquivel
what about tyr 9:12
and all of the hydroxyl one?
9:12
Nkechiamaka Nwosu
what is a nucleophile and an electrophile?
9:12
Marcos Oliveira
all AA capable of donating and titratable that have a proton to donate
9:13
Jennifer Ma
table 4.1
9:13
Beth Williams
Can you please explain how allosteric enzymes work?
9:13
Marcos Oliveira
like Hb!! they have quaternary structure and activation of one subunit "elbows" the other into being
active 9:15
Margaret Gogola
are we going to cover ch 7 tomorrow? 9:16
Beth Williams
So they basically communicate with the other molecules to bind to O2 so they are all the same? 9:16
Marcos Oliveira
yes we are covering chpt 7 tomorrow the essentials
9:16
Margaret Gogola
will what we cover be on this weeks or next week's test?
9:17
Marcos Oliveira
You need to think in general terms. We are talking about an enzyme not O2 binding yet all of the
behavior mirrow our discussion of Hb 9:17
yes Chpat 7 will be on this test 9:17
Danellie Barrera
what determines the most/least conservative amino acid substitution? 9:18
Lilia Esquivel
can you explain the importance of the histidine with hemoglobin?
9:18
Margaret Gogola
ok thank you
9:18
Marcos Oliveira
His coordinates Fe found at the porphorin ring and a second His interacts with the Heme group on the
opposite side they are found conserved in both Hb and Mb
9:19
Lilia Esquivel
ok
9:20
Danellie Barrera
what determines the most/least conservative amino acid substitution? 9:21
Marcos Oliveira
conservative mutation is one where shape and property are minimally changed 9:22
Beth Williams
When talking about competitive inhibtion, is there something that "trumpts" this or will this competitive
enzyme always win?
9:25
Marcos Oliveira
not sure I undertand the question. We discuss competitive inibitor which affects enzyme activity 9:26
Beth Williams
so when competitive inhibition is present the enzymes work more efficiently or bind more?
Marcos Oliveira
9:29
when a competitive inhibitor binds it affects Km 9:30
It prevents natural substrate from binding
9:30
Beth Williams
thanks! 9:30
Rebeca Jimenez
will we be expected to manipulate the michaelis-menten equation, or just memorize the final equation
listed on page 188? [7-21]
9:33
Beth Williams
Is cooperative binding done at the FG site?
9:34
Marcos Oliveira
no derivation of MM simply how to use it and understanding what Km and kcat mean
Rebeca Jimenez
k
9:34
Marcos Oliveira
in Hb FG plays a role in communication between subunits (cooperativity)
Beth Williams
:)
9:35
Marcos Oliveira
Any last question
9:36
Margaret Gogola
do we need to know the G equations
9:38
g products- g reactants...spontaneous...non spontenous?
Marcos Oliveira
no free energy equations
9:38
Margaret Gogola
i remember a little about that fomr discussion 9:39
9:38
9:34
9:34
great :) 9:39
Beth Williams
Really quick...what do effectors do? How do they effect the catalytic activity?
9:41
Marcos Oliveira
effectors like [H=} in Hb either have an activation effect or inhibitory effect we will discuss this
tomorrow
9:42
Beth Williams
ok...thanks:)
9:42