Amino acid catabolism (Transamination | Deamination | Urea cycle)

00:07:24
https://www.youtube.com/watch?v=0OMNyVzLnVc

Summary

TLDRThe video discusses amino acid catabolism, focusing on how proteins are broken down into amino acids and subsequently into nitrogen for excretion. It highlights the role of enzymes in protein degradation, the conversion of amino acids to glutamate through transamination, and the detoxification of ammonia into urea via the urea cycle in the liver. Key processes such as transamination, deamination, and the urea cycle are explained, along with the enzymes involved in these reactions. The video serves as an overview, with a promise of more detailed discussions in future videos.

Takeaways

  • 🔍 Overview of amino acid catabolism
  • 💡 Role of enzymes in protein degradation
  • 🔄 Transamination process explained
  • ⚗️ Conversion of amino acids to glutamate
  • 💧 Ammonia detoxification into urea
  • 🏥 Urea cycle occurs in the liver
  • ⚠️ Toxicity of ammonia
  • 🔑 Importance of pyridoxal phosphate
  • 🔄 Key steps in the urea cycle
  • 📚 Future detailed discussions promised

Timeline

  • 00:00:00 - 00:07:24

    In this video, the host introduces the topic of amino acid catabolism, explaining how proteins are broken down into amino acids in the stomach and intestines with the help of enzymes. The focus is on the molecular breakdown of amino acids, highlighting the conversion of the amine group into ammonia, which is then excreted as urea, while the carbon skeleton is utilized in biosynthetic pathways. The liver is identified as the central hub for amino acid catabolism, where transamination occurs, converting amino acids into glutamate, which then undergoes deamination to release ammonia. The video outlines the urea cycle, detailing how ammonia is converted into urea for excretion, emphasizing the importance of enzymes like aminotransferases and glutamate dehydrogenase in these processes. The host concludes by mentioning that further details on the urea cycle and transamination will be covered in future videos, encouraging viewers to like, share, and subscribe.

Mind Map

Video Q&A

  • What is amino acid catabolism?

    Amino acid catabolism is the process of breaking down amino acids into simpler compounds, including nitrogen for excretion.

  • What enzymes are involved in protein breakdown?

    Enzymes such as trypsin, chymotrypsin, and carboxypeptidase help degrade proteins into amino acids.

  • What happens to the amine group of amino acids?

    The amine group is converted into ammonia, which is then transformed into urea for excretion.

  • Where does amino acid catabolism primarily occur?

    Amino acid catabolism primarily occurs in the liver.

  • What is transamination?

    Transamination is the process where amino acids donate their amine group to form glutamate.

  • What is the urea cycle?

    The urea cycle is a series of biochemical reactions that convert ammonia into urea for excretion.

  • What is the role of glutamate in amino acid catabolism?

    Glutamate acts as a key intermediate in the conversion of amino acids to ammonia.

  • Why is ammonia toxic?

    Ammonia is toxic because it is highly soluble in blood and can cause brain toxicity if not properly excreted.

  • What is the significance of pyridoxal phosphate in transamination?

    Pyridoxal phosphate is a crucial cofactor for the activity of aminotransferases in transamination.

  • What are the main steps in the urea cycle?

    The urea cycle involves the conversion of ammonia to urea through several intermediates, including citrulline and arginine.

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  • 00:00:01
    hi everyone welcome to my channel
  • 00:00:03
    and in this video we'll talk about amino
  • 00:00:07
    acid
  • 00:00:08
    catabolism so we are going to get an
  • 00:00:11
    overview how protein is broken down to
  • 00:00:14
    amino acids
  • 00:00:15
    and how these amino acids are broken
  • 00:00:18
    down to
  • 00:00:19
    nitrogen and how it is excreted
  • 00:00:24
    so we know that in our
  • 00:00:27
    stomach in our intestine with the help
  • 00:00:30
    of several enzymes such as trypsin
  • 00:00:32
    chymotrypsine
  • 00:00:33
    carboxy peptidase peptine all of these
  • 00:00:36
    things
  • 00:00:37
    degrade proteins into the simplest form
  • 00:00:40
    which is amino acid
  • 00:00:42
    and the amino acid is absorbed in the
  • 00:00:45
    intestinal epithelial cells
  • 00:00:47
    and then it moves into the blood which
  • 00:00:50
    is
  • 00:00:50
    actually used to make muscle proteins
  • 00:00:54
    or other aspects right
  • 00:00:57
    but in this video our focus is how
  • 00:01:01
    protein breakdown occurs at a molecular
  • 00:01:04
    level
  • 00:01:05
    so proteins are broken down into amino
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    acid
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    that is the basic uh constituent of a
  • 00:01:12
    protein
  • 00:01:13
    now this amino acid is further broken
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    down
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    the amine part of the amino acid
  • 00:01:20
    generates ammonia which is further
  • 00:01:23
    excreted as
  • 00:01:24
    urea whereas the carbon skeleton
  • 00:01:28
    is recycled and used in several
  • 00:01:31
    biosynthetic pathways such as
  • 00:01:32
    tca cycle now in this video we'll look
  • 00:01:36
    at
  • 00:01:36
    the overview of a amino acid catabolism
  • 00:01:41
    so amino acid catabolism the hub of
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    amino acid catabolism is the liver
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    so imagine there are four amino acids so
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    each of these amino acid would donate
  • 00:01:50
    their amine group to a substance
  • 00:01:54
    which is ultimately glutamate
  • 00:01:57
    so it would generate glutamate from
  • 00:02:00
    glutamate
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    ammonia would be generated and alpha
  • 00:02:05
    ketoglutarate would be
  • 00:02:07
    a side product of it now this ammonia
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    is extremely harmful and toxic so
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    ammonia would be converted into a less
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    harmful
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    form which is actually urea and urea
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    is the form which is excreted right
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    now the process of conversion of several
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    amino acid to glutamate is known as
  • 00:02:30
    transamination
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    where these amino acids donate their
  • 00:02:34
    amine group to glutamate
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    now from glutamate the process of
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    generation of ammonia is known as
  • 00:02:42
    deamination
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    and lastly the urea cycle generates
  • 00:02:46
    urea from ammonia so this
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    is the overall workflow of
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    amino acid catabolism so let's look into
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    this
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    process in bit more details so the first
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    step
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    is nothing but breaking down of amino
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    acid
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    into glutamate or funneling it into
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    glutamate
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    and all happens inside the liver
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    hepatocytes so in the liver hepatocytes
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    any amino acid
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    gets converted into a keto acid and this
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    process is known as transamination
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    or this is just a amine group transfer
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    reaction so the amine group is
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    transferred to what moiety
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    so the amine group is transferred with
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    the help of aminotransferases
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    and the amine group acceptor is nothing
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    but alpha ketoglutaric acid
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    it accept the amine group from the amino
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    acid and itself get converted to
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    glutamate
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    so from different kind of amino acid
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    we get the amine group funneled in form
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    of
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    glutamate and the key enzyme here is the
  • 00:03:53
    amino transference
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    the amino transferase plays an important
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    role in transamination
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    and the key prosthetic group here is
  • 00:04:01
    pyridoxal phosphate
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    so plp is very important for the
  • 00:04:05
    functionality of the
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    amino transferases now let's talk about
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    the next step
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    we have glutamate and the ammon the
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    amine group
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    is now in format of the glutamate this
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    amine group
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    would be released from the glutamate by
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    the help of glutamate dehydrogenase
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    enzyme
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    this glutamine dehydrogenase enzyme
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    converts glutamate into a
  • 00:04:30
    alpha immunoglutarate intermediate from
  • 00:04:32
    which it gets converted to
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    alpha-ketoglutaric acid
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    ultimately the ammonia is released but
  • 00:04:39
    the problem is this ammonia is highly
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    toxic
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    it is highly soluble in the blood so if
  • 00:04:44
    it is not excreted in proper
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    method then it would generate huge
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    problem and it can even generate
  • 00:04:50
    toxicity in the brain
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    so this ammonia has to be processed in
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    some way
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    which is less harmful and it would be
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    excreted and that excretion format is
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    known as
  • 00:05:02
    urea so ammonia gets converted to urea
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    by the process of urea cycle so
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    we'll talk about the urea cycle in bit
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    more details
  • 00:05:13
    so urea cycle takes part in the liver
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    especially in the liver hepatocyte
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    inside the liver hepatocyte a portion of
  • 00:05:20
    the urea cycle takes place in the
  • 00:05:22
    mitochondria and portion takes place in
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    the cytoplasm
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    so in the mitochondria we have quite a
  • 00:05:27
    lot of ammonia which was derived
  • 00:05:29
    from glutamate by by glutamate
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    dehydrogenase
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    and the reaction is known as
  • 00:05:38
    deamination right now
  • 00:05:42
    from ammonia carbohydrate phosphate
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    is generated with the help of the enzyme
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    carbomole phosphate
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    synthetase and in this process as the
  • 00:05:52
    name suggests
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    you need atp to trigger this process and
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    atp is utilized
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    to generate carbohydrate phosphate
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    carbohydrate is
  • 00:06:00
    the first product of urea cycle
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    carbohydrate
  • 00:06:04
    combines with another product called
  • 00:06:06
    ornithine which is already present in
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    the liver mitochondria
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    both of them gets combined and form
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    citrulline and via several intermediates
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    such as aspartate arginosuccinate
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    arginine
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    it regenerates the ornithine which is
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    ready
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    for another round of urea cycle now the
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    key step
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    in this process is the conversion of
  • 00:06:30
    arginine
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    to ornithine when argentine gets
  • 00:06:33
    converted to ornithin or anything is
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    regenerated
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    but at the same time urea is
  • 00:06:40
    released so urea is excreted
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    in this way so we understood
  • 00:06:46
    in this video that what is the overview
  • 00:06:50
    of amino acid catabolism how does the
  • 00:06:53
    process of transamination deamination
  • 00:06:55
    and urea cycle work
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    we have also looked at the enzymes which
  • 00:06:59
    are involved in transamination
  • 00:07:00
    deamination and urea cycle
  • 00:07:02
    and in this video we have not talked
  • 00:07:04
    about urea cycle or transamination
  • 00:07:06
    process in
  • 00:07:07
    details so in other videos we'll talk
  • 00:07:09
    about
  • 00:07:10
    these processes in way more details but
  • 00:07:12
    this was just an
  • 00:07:13
    overview to give you a big picture so i
  • 00:07:16
    hope you enjoyed this video if you like
  • 00:07:17
    this video give it a quick thumbs up
  • 00:07:19
    don't forget to like share and subscribe
  • 00:07:20
    and thank you
Tags
  • amino acids
  • catabolism
  • protein breakdown
  • transamination
  • deamination
  • urea cycle
  • glutamate
  • ammonia
  • liver
  • enzymes