Lecture 14 - Lecture14 Lecture14: ,thecarbon CO2 and O2...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 14 Lecture 14: Amino Acid and Urea Metabolism - amino acids lose their amino groups and become  -keto acids, the “carbon α   skeletons” of amino amino acids - The  -keto acids undergo oxidation to  α 2 CO  and  2 O  in citric acid cycle, or  provide 3-4C units that can be converted by gluconeogenesis into glucose 18.1 Metabolic Fates of Amino Groups - most a.a. are metabolized in the liver - some of the ammonia generated is recycled and used in biosynthetic pathways;  the excess is excreted directly or converted to urea for excretion - Gluatmate and Glutamine are the collection points for amino groups - In cytosol of liver: amino groups from amino acids are transferred to  - α ketoglutarate  to form  glutamate  which enters mitochondria and gives up amino  group as  4 NH + - Excess ammonia generated in other tissues is converted to the amide nitrogen  of  glutamine , which passes to the liver and then to liver mitochondria  - In muscle, excess a.a. are transferred to pyruvate  to form  alanine , another  transporter of amino groups to the liver Pyridoxal Phosphate participates in the transfer of  -amino groups to  -ketoglutarate  α α first remove the  -amino group by  α aminotransferase the  -amino group is transferred to the  -carbon atom of  α α α -ketoglutarate and  leaving behind  α -ketoacid Transamination collects the amino groups from many different a.a. in the form of  L-glutamate; glutamate functions an amino group donor for biosynthetic  pathways or excretion pathways Aminotransferases of  pyridoxal phosphate (PLP)  the coenzyme, of vitamin B 6 Functions are an intermediate carrier of amino groups at the active site of amino- transferases  It is covalently bound to the enzyme’s active site through an aldimine (Schiff  base) linkage to the  ε -amino group of a Lys residue Aminotransferases are Ping-Pong reactions: the incoming amino acid binds to the  active site, donates it amino group to pyridoxal phosphate, departs in the form of a  -keto acid α Incoming  -keto acid binds, accepts the amino group from pyridoxamnine α   phosphate and departs in form of amino acid Glutamate Releases It Amino Group As Ammonia in the Liver - in liver: glutamate is transported from cytosol into mitochondria to undergo  oxidative deamination  by  L-glutamate dehydrogenase 1 of 8
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Lecture 14 - In mammals, the enzyme uses NAD+ or NADP+ as the acceptor of reducing  equivalents  - The  -ketoglutarate formed from glutamate deamination can  be used in the α   citric acid cycle and for glucose synthesis Glutamine transports ammonia in the bloodstream
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern