Chymotrypsin Mechanism | Biochemistry

00:11:19
https://www.youtube.com/watch?v=j5JBT1xj96o

Résumé

TLDRچىموتىرىپسىن بىر ئانزىم بولۇپ ، ئۇ فېنىلالانىن ، تىروزىن ياكى تىرىپتوفان قاتارلىق سەرۋەتلىك قالدۇقلاردىن كېيىن بۆلىكلىنىدۇ. بۇ پائال يېرىمدە بىر بىرى بىلەن ئىككى خىل ئامىن كىسلاتا قىسقۇچى بار، ئۇ ئاقساقلانغان چېپىشىپ، كاتالىتىك ئىككەلىككە ئايلاندۇرايدۇ. سەرىن ئىككى ئېچىق ئاستىدىكى مۇۋاپىق بار، ئۇ ئاسپارتات 102، تىزىدىن 57، سىرىن 195 بويىچە بىرلىكلىك زاۋدۇر.

A retenir

  • 🔬 چىموتىرىپسىن پائالىيت ئورتورىسىدە فېنىلالانىن، تىروزىن ياكى تىرىپتوفاندىكى بوشلۇقنى قاپلىشىدۇ.
  • 💧 كاتالىتسىن ئىككىلەندۈرۈشكى بولار، مۇۋاپىق بىرلىكتە ئامىن كېلىپ قۇرۇقلۇق ئېيىلاش قىلىدۇ.
  • 📈 ئاسپارتات، تىزىدىن ۋە سېرىنى ئىشلىتىپ، ئوكسىئانىئون بۇزلۇش قانداق خەلقاراغا ئەمەلىيەتەن قىلات.
  • 🔄 تىكەنسىز بولۇش مودىنى كۈزىتكى كۆرۈش، ھەتتا ئىككى خىل كېلىپ قېلىدۇ.
  • 🌀 ئامىنلىرىمىز چىمۇچىن گفتاسنى بۇزۇش بۇحار ئامىن بولۇپ چەرۈخىڭنىڭ پېتىچەمە گىمۇچى يولغا بۇنىڭغا يېتىلەر.
  • 🔄 چىموتىرىپسىننىڭ بەزى ئوكسىئانىئون ھولدا ئۆلكەشلىرى بار.
  • ⚖️ بىر خىل قويمېي جىنايىتىگە ياكى ئوكسىئانىئون ئاندوراق ئېيغىز قىلىدۇ.
  • 🚀 مۇھىم بىر بوغچە قانداقىلىپ خۇسەن ئاكساڭ ۋاقتى ئۆز ئىكەلىك بۇلۇپ.
  • 🧩 ياڭخور قىسقى بويىچە، قوغداپ ئىنىش كېلىدۇ.
  • 🔁 سەرىننىڭ ھاياتشار ئوچشەن بىرە بايپۇلعەك ئۈستىگە ياردەم بەرگۈچىلەرنىڭ مېھانىز مىجىز يولغا ئىشلىتىلىدۇ.

Chronologie

  • 00:00:00 - 00:05:00

    chymotrypsin نى ماددىكتى ئانزىم بولۇپ، خىمىيىلىك ئەروماتىك توپلىق ۋاكالەتچىلەرنى بۆلەلىينىدۇ. بۇ ماددىنىڭ ئاكتىپ ئىكەنلىكىنى چۈشەندۈرۈپ، hydrophobic جىق قاچىسى ۋە oxyanionھۆل ۋە شۇنداقلا بىرىكمە ياردەم بارلىقىنى بىلدۈرۈشى ۋە ئاكتىپ چاپلىق ئورنىدا ئۈچ خىل ئامىن كىسلاتانى ئۆز ئىچىگە ئالغان ASP102، HIS57، SER195 بىلىشىمىز كېرەك، ئۇلار بىراق بولسا بىرلىكتە ئىشلىتىپ، ئاكتىپ چاپلىق ئورنىدا ھەرىكەت قىلىپ، كەينىدىكى ئەزۇۋا بەلەد ۋاقتىدا تەقدىم قىلىدۇ.

  • 00:05:00 - 00:11:19

    chymotrypsin خىمىيىلىك ئىكەملىككە كىرىپ، ئەنزەيمنىڭ باشقا بىر قىسىم يەرلەرنى ۋە خىمىيىلىك بوندىلارنى بۆلۈش نىشانلىرىغا كۈچلۈك تەسىر كۆرسىتىدۇ. نىتروجېن ئورنىنىڭ ھىمياۋىغا قىستۇرۇش كېزكىن كىرىشىدە ھىمايەلەش ئۈچۈن ئەرزۈمەن بىر شەرتلەر شەكىللىنىدۇ ۋە ئەڭ ياخشى بەزىنىڭ重新 ئورنىنى ئورۇنلاشتۇرۇدۇ. HISTIDINE بەلەندىلەرنىڭ ئۈستىدە كۈچلۈك تەسىر كۈزىتىلىدۇ ۋە تەجىريبە ئۇطۇق ئىلگىرىلەپ، ئاكتىپ چاپلىق ئورۇنىڭدا بىر خىل خاتىرە كۆرۈلىدۇ. بۇ ئۇسلۇب باشقۇرۇلمىغان بولۇپ، ئەروماتىك بوندۇنلار ئەمەلىي ئەلپۇك قىسىم قىلغاندىن كېيىن بولىدۇ.

Carte mentale

Mind Map

Questions fréquemment posées

  • چىموتىرىپسسنىڭ مۇھىم بۆلۈملىرى قايسىلار؟

    چىموتىرىپسسنىڭ پائال يەرلىرى بىرى hydrophobic pocket، oxyanion hole، گلېسەرە ئىۋازىغا قۇغۇرتاپتىن، سيرابىدلگە كاتالىتكۈمتۈكلىكتە خامبىل ۋە تىزىدىن ۋۇكۇن سېرىن، বাৰكاگېن ئامىن كىسلاتا قاتناشقۇچ قىلغانلاشى جاھىم بۇزا چىقىدۇ.

  • چىموتىرىپسندا نەچچە بولۇپ قالغۇچى بىر تۈپ ھوال ئەگىشلەيدۇ؟

    چىموتىرىپسندا ئۈچى ئۇيغۇرخانات ئاسپارتات 102، تىزىدىن 57، سيرىن 195 كېلىدۇ بولۇپ قالغۇچى بىر تۈپچەت نەچچە ھوال ھوقاسى چۈشەندە چىچەكچىلىكتە بەرپاچى چىقىدۇ.

  • چىموتىرىپسس مەركەپ كۈندە كۆدەچ؟

    چىموتىرىپسس مەركەپلەر ئۇچۇر, يەرگۈچ اۆكسىئان ھولە قۇشۇرغاندىن كېيىن تىزىدىن ئالماشتۇرغاندىن كېیىن ئامىن كىسلاتالىق پازىك كەندۈندە تەڭشەلمە شېكىلدىن كېيىن بۇيەك ئىككى خىل چاڭ جۈپگە بولۇپ بەرپا قىلالىدۇ.

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Sous-titres
en
Défilement automatique:
  • 00:00:01
    chymotrypsin is an enzyme that cleaves
  • 00:00:04
    after aromatic residues such as
  • 00:00:07
    phenylalanine tyrosine or tryptophan
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    within the active site of chymotrypsin
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    we see a hydrophobic pocket
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    an oxyanion whole
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    a glycine residue
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    and three different amino acids over
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    here
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    now these three amino acids aspartate
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    102 histidine 57 serine 195
  • 00:00:34
    form a catalytic triad
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    meaning that these three amino acid
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    residues work together in the active
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    site in order to cleave our peptide bond
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    after the aromatic residue
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    now what do these numbers mean at the
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    top of each of these amino acids
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    this number represents the location at
  • 00:01:00
    which this amino acid occurs
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    so we know that
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    when we have amino acid chains we have
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    lots of amino acids so aspartate occurs
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    at position number 102 whereas histidine
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    occurs at position number 57 and serine
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    at 195.
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    now we also have this glycine residue
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    which is actually going to be
  • 00:01:23
    stabilizing our oxyanion
  • 00:01:26
    which we'll see later in the steps
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    now the hydrophobic pocket is where our
  • 00:01:31
    hydrophobic group is going to sit
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    so when we take a look at phenylalanine
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    tyrosine and tryptophan they all have
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    very bulky aromatics that are
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    hydrophobic
  • 00:01:43
    and these hydrophobic
  • 00:01:45
    parts of these amino acids will reside
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    over here and this in a way keeps the
  • 00:01:52
    keeps the polypeptide in place while it
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    is being cleaved
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    now in the first step we add in our
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    substrate which is our polypeptide
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    and we add it into the active site
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    when it enters its active site remember
  • 00:02:10
    we are reading the polypeptide from left
  • 00:02:13
    to right so we'll cleave it after the
  • 00:02:15
    aromatic so we will cleave it at this
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    peptide bond between the carbon and the
  • 00:02:22
    nitrogen
  • 00:02:23
    this is where we are going to cleave
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    now if we take a look over here we can
  • 00:02:29
    see that
  • 00:02:31
    uh this this
  • 00:02:33
    histidine is attacking the hydrogen on
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    the serine
  • 00:02:38
    now we have to think why is this
  • 00:02:40
    happening this is happening because when
  • 00:02:43
    the substrate enters the active site of
  • 00:02:46
    chymotrypsin
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    the enzyme chymotrypsin
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    um goes through a little bit of a
  • 00:02:52
    conformational change in order to fit
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    the substrate and this is referred to as
  • 00:02:57
    induced fit
  • 00:02:59
    so when induced fit occurs and the
  • 00:03:02
    substrate binds this compresses the bond
  • 00:03:06
    between aspartate and histidine remember
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    we have a bond right over here between
  • 00:03:11
    aspartate and histidine
  • 00:03:14
    the negatively charged oxygen is
  • 00:03:16
    interacting with that hydrogen so when
  • 00:03:19
    our substrate is added in this bond is
  • 00:03:23
    actually compressed
  • 00:03:25
    so normally histidine has a pka value of
  • 00:03:29
    six
  • 00:03:30
    okay that's our normal pka value but
  • 00:03:33
    after this uh bond compresses
  • 00:03:37
    the pka of histidine changes to over 12.
  • 00:03:42
    and we know we know that pka it's
  • 00:03:47
    the potential of
  • 00:03:49
    dissociating
  • 00:03:51
    donating our hydrogens
  • 00:03:53
    but we know also know that our
  • 00:03:56
    environment so the molecules or
  • 00:03:58
    substituents that are surrounding uh
  • 00:04:01
    surrounding our molecule are going to
  • 00:04:03
    affect the
  • 00:04:04
    the pka value so since this bond
  • 00:04:07
    compresses it affects the histidine and
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    now the pka has increased to 12. so
  • 00:04:13
    since the pka has increased to past 12
  • 00:04:17
    this makes histidine a very good base
  • 00:04:19
    now and we know that bases the
  • 00:04:21
    definition of a base is that
  • 00:04:23
    it will
  • 00:04:25
    be a very good uh proton acceptor
  • 00:04:29
    so it will want a proton so that is why
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    we see histidine over here abstracting
  • 00:04:34
    that proton from serine because it's a
  • 00:04:37
    very good base and it has that nitrogen
  • 00:04:39
    has that lone pair so it's going to
  • 00:04:41
    abstract that hydrogen
  • 00:04:42
    but now this oxygen on the serine
  • 00:04:47
    is going to gain a lone pair
  • 00:04:49
    now this lone pair is now
  • 00:04:53
    going to create a negatively charged
  • 00:04:54
    oxygen which is going to
  • 00:04:56
    nucleophilically attack this carbon over
  • 00:04:59
    here now this carbon is part of our
  • 00:05:02
    polypeptide which has entered the
  • 00:05:04
    substrate
  • 00:05:05
    so when this oxygen nucleophilically
  • 00:05:07
    attacks this carbon we know that carbon
  • 00:05:10
    can only have four bonds
  • 00:05:12
    so what's going to happen is that carbon
  • 00:05:14
    is going to break one of its bonds and
  • 00:05:15
    it's going to be this
  • 00:05:18
    one over here so oxygen is going to gain
  • 00:05:20
    a lone pair okay and we'll see that on
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    the next slide
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    so here we can see that oxygen has
  • 00:05:28
    gained a lone pair
  • 00:05:30
    and it's gained a negative charge
  • 00:05:32
    we can
  • 00:05:33
    also see that the serine
  • 00:05:35
    this oxygen remember that this oxygen
  • 00:05:38
    just nucleophilically attacked this
  • 00:05:39
    carbon in the previous step
  • 00:05:42
    we can also see that histidine now has
  • 00:05:44
    formed a covalent bond with hydrogen
  • 00:05:48
    now what's going to happen is that
  • 00:05:50
    this is a very short-lived intermediate
  • 00:05:53
    okay
  • 00:05:54
    this is the tetrahedral intermediate and
  • 00:05:57
    this is very very interesting this is
  • 00:06:00
    called the tetrahedral intermediate
  • 00:06:02
    because now carbon has four bonds four
  • 00:06:05
    different bonds before it only had three
  • 00:06:08
    now it has four so this is our first
  • 00:06:10
    tetrahedral intermediate
  • 00:06:12
    and this is a very short-lived unstable
  • 00:06:15
    intermediate because of this oxyanion
  • 00:06:18
    now what's important to note over here
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    is that this oxygen is actually inside
  • 00:06:22
    that oxyanion hole we were talking about
  • 00:06:25
    it's positioned in this oxyanion whole
  • 00:06:27
    so it can interact with the hydrogen of
  • 00:06:29
    glycine and the hydrogen of serine and
  • 00:06:33
    they're interacting via hydrogen bonding
  • 00:06:35
    which is stabilizing this oxyanion but
  • 00:06:38
    it's still a relatively uh unstable so
  • 00:06:41
    oxygen is going to regain that double
  • 00:06:43
    bond it had with carbon and as it does
  • 00:06:45
    so
  • 00:06:46
    uh carbon can only have four bonds so it
  • 00:06:48
    must lose another bond
  • 00:06:50
    and it's going to be this one over here
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    this uh this bond over here this
  • 00:06:54
    structure over here is a very good
  • 00:06:56
    leaving group
  • 00:06:57
    so
  • 00:06:58
    it's going to break off now as this bond
  • 00:07:02
    breaks off this nitrogen over here is
  • 00:07:04
    going to gain a lone pair
  • 00:07:06
    and it's it's going to have that extra
  • 00:07:08
    lone pair and nitrogen normally wants to
  • 00:07:10
    have three bonds so as it's leaving
  • 00:07:14
    it's going to abstract the hydrogen on
  • 00:07:16
    that histidine
  • 00:07:17
    so as it leaves we can see over here as
  • 00:07:21
    it left it abstracted that hydrogen on
  • 00:07:24
    the histidine
  • 00:07:25
    and this is our first product now
  • 00:07:27
    remember this was originally part of our
  • 00:07:28
    polypeptide
  • 00:07:30
    but now it has become our first product
  • 00:07:33
    and this is what we are left with we are
  • 00:07:35
    left with our acyl enzyme intermediate
  • 00:07:39
    so
  • 00:07:40
    once again we can note over here is that
  • 00:07:41
    this oxygen has regained its double bond
  • 00:07:44
    and we are still bound to serine
  • 00:07:47
    now we have to break this part of our of
  • 00:07:50
    our fragment that we are left with
  • 00:07:54
    now in this step we can see that we have
  • 00:07:56
    our acyl enzyme intermediate and what's
  • 00:07:59
    gonna happen is that we're gonna add
  • 00:08:01
    water now water is a great molecule to
  • 00:08:04
    add in mechanisms because
  • 00:08:08
    oxygen um has two hydrogens which can be
  • 00:08:11
    abstracted now remember this histidine
  • 00:08:14
    it still has that pka
  • 00:08:17
    value greater than 12 so it's still a
  • 00:08:19
    really good base
  • 00:08:21
    because the bond between the aspartate
  • 00:08:23
    and the histidine has been compressed
  • 00:08:25
    and it's increasing that pka of
  • 00:08:27
    histidine
  • 00:08:28
    so the nitrogen on histidine is going to
  • 00:08:31
    abstract that hydrogen and oxygen over
  • 00:08:34
    here on the water is going to gain a
  • 00:08:35
    lone pair and it's going to
  • 00:08:36
    nucleophilically attack that same carbon
  • 00:08:39
    again now once it does so we see the
  • 00:08:41
    same thing happen this oxygen gains a
  • 00:08:43
    lone pair gains a negative charge it's
  • 00:08:45
    going to become an oxyanion within this
  • 00:08:47
    oxyanion whole and we'll see in the next
  • 00:08:49
    step that this charge is going to be
  • 00:08:51
    stabilized with the serine and glycine
  • 00:08:52
    once again
  • 00:08:55
    so over here we see that
  • 00:08:58
    the glycine and serine are stabilizing
  • 00:09:00
    that negative charge we can see that
  • 00:09:02
    histidine has abstracted that hydrogen
  • 00:09:04
    from the water and now it has a covalent
  • 00:09:06
    bond with hydrogen but now what's going
  • 00:09:08
    to happen is that once again this
  • 00:09:10
    oxyanion this is a this is our second
  • 00:09:13
    tetrahedral intermediate because carbon
  • 00:09:15
    has four bonds
  • 00:09:17
    and once again the
  • 00:09:19
    unstable oxyanion it's going to reform
  • 00:09:21
    that bond that it had with carbon and
  • 00:09:23
    remember that carbon can only have four
  • 00:09:25
    bonds so it's going to lose a bond so
  • 00:09:27
    now this is going to be our good leaving
  • 00:09:29
    group and this bond is going to break
  • 00:09:31
    so when this bond breaks this oxygen
  • 00:09:33
    gains a lone pair and once it gains a
  • 00:09:35
    lone pair it's more it wants to abstract
  • 00:09:38
    its hydrogen remember that in our first
  • 00:09:40
    step serine lost its hydrogen to
  • 00:09:43
    histidine now it's coming back and
  • 00:09:45
    saying hey i want my hydrogen back
  • 00:09:47
    so it's going to abstract its hydrogen
  • 00:09:49
    back
  • 00:09:51
    now over here we can see that serine
  • 00:09:54
    has abstracted its hydrogen
  • 00:09:57
    and now we are left with this this part
  • 00:10:01
    of our
  • 00:10:03
    this part of
  • 00:10:04
    our original polypeptide which is now
  • 00:10:06
    going to break off and become
  • 00:10:08
    our second product
  • 00:10:10
    now
  • 00:10:12
    um this oxygen is still in its oxyanion
  • 00:10:15
    whole and we still see the
  • 00:10:18
    phenylalanine inside that hydrophobic
  • 00:10:20
    pocket which is keeping the entire
  • 00:10:22
    molecule of the overall
  • 00:10:24
    fragment in place
  • 00:10:27
    now in the next step we can see over
  • 00:10:28
    here this is the same depiction as the
  • 00:10:30
    previous slide where serine has
  • 00:10:33
    abstracted its hydrogen
  • 00:10:35
    we're left with this part of the
  • 00:10:36
    fragment and now this part of the
  • 00:10:38
    fragment is going to be released from
  • 00:10:39
    the active site and this is our second
  • 00:10:41
    product and then we are back to our
  • 00:10:44
    original state where we have our
  • 00:10:46
    catalytic triad where they're
  • 00:10:48
    interacting with one another oxy anion
  • 00:10:50
    whole is empty again hydrophobic pocket
  • 00:10:52
    is empty again and we are ready to go
  • 00:10:54
    for another round of cleavage
  • 00:10:57
    and that is essentially the chymotrypsin
  • 00:10:59
    mechanism if we understand the first
  • 00:11:01
    half the second half is exactly the same
  • 00:11:04
    we end up with two products
  • 00:11:07
    um we end up with two products and
  • 00:11:10
    remember that enzymes do not get used up
  • 00:11:12
    or changed in a reaction
  • 00:11:14
    so whatever we start with that's what we
  • 00:11:17
    must end with
Tags
  • Enzyme
  • Chymotrypsin
  • Catalytic Triad
  • Amino Acids
  • Peptide Bond
  • Aromatic Residues
  • Hydrophobic Pocket
  • Oxyanion Hole
  • Induced Fit
  • Tetrahedral Intermediate