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1. Introduction to biochemistry
- Prof. Gerald W. Feigenson
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2. Amino acids and peptides
- Prof. Gerald W. Feigenson
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3. Protein structure principles
- Prof. Gerald W. Feigenson
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4. Observed protein structures
- Prof. Gerald W. Feigenson
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5. Protein folds and IV structure
- Prof. Gerald W. Feigenson
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6. Protein stability and folding
- Prof. Gerald W. Feigenson
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7. Haemoglobin structure and stability
- Prof. Gerald W. Feigenson
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8. Enzyme specificity and catalysis
- Prof. Gerald W. Feigenson
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9. Enzyme kinetics (Michaelis-Menten)
- Prof. Gerald W. Feigenson
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10. Enzyme inhibition; chymotrypsin
- Prof. Gerald W. Feigenson
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11. Enzyme regulation and coenzymes
- Prof. Gerald W. Feigenson
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12. Lipids, biomembranes and membrane proteins
- Prof. Gerald W. Feigenson
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13. Structure and function of carbohydrates
- Prof. Gerald W. Feigenson
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14. Metabolism principles
- Prof. Gerald W. Feigenson
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15. Glycolysis - energy and useful cell chemicals
- Prof. Gerald W. Feigenson
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16. Glycolysis control
- Prof. Gerald W. Feigenson
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17. Metabolism of pyruvate and fat
- Prof. Gerald W. Feigenson
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18. Urea cycle; oxidative phosphorylation 1
- Prof. Gerald W. Feigenson
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19. Urea cycle; oxidative phosphorylation 2
- Prof. Gerald W. Feigenson
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20. Light-driven reactions in photosynthesis
- Prof. Gerald W. Feigenson
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21. Gluconeogenesis and the Calvin cycle
- Prof. Gerald W. Feigenson
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22. Synthesis of lipids and N-containing molecules 1
- Prof. Gerald W. Feigenson
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23. Synthesis of lipids and N-containing molecules 2
- Prof. Gerald W. Feigenson
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24. Hormone mechanisms
- Prof. Gerald W. Feigenson
Printable Handouts
Navigable Slide Index
- Introduction
- Lecture outline
- Form of ionisable groups at any pH
- Generalities of the amino acid side chains
- Aliphatic amino acids
- Aromatic amino acids
- Some H-bond properties
- S - containing amino acids
- Aliphatic-OH amino acids
- Acidic amino acids
- Amide amino acids
- Basic amino acids
- Proline
- How to group amino acid side chains
- Peptides
- The hydrophobic interaction (1)
- The hydrophobic interaction (2)
- Side chain behaviour in peptides
- Proteins: general infromation
- Myoglobin behaviour
- How does O2 bind to myoglobin?
- In H2O without a protein, haem does not bind O2
- Lecture summary
Topics Covered
- Ionisable groups
- Amino acid properties
- Amino acid classification
- Peptides
- Hydrophobic interactions
- Myoglobin
Talk Citation
Feigenson, G.W. (2022, November 27). Amino acids and peptides [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved October 8, 2024, from https://doi.org/10.69645/HDHT5784.Export Citation (RIS)
Publication History
Financial Disclosures
- Gerald Feigenson has no commercial/financial relationships to disclose.
Request access to the Principles of Biochemistry lecture series, an extensive introductory to the field of biochemistry. An HSTalks representative will contact you with more information about this series and getting unrestricted access to it.
A selection of talks on Biochemistry
Transcript
Please wait while the transcript is being prepared...
0:00
Greetings. Welcome to this Principles of Biochemistry lecture series.
I am Jerry Feigenson.
I'm a professor in
the Department of Molecular Biology and Genetics at Cornell University in the USA.
In the first lecture,
we saw that matter in the universe is organized on all size scales.
The size scale of biochemistry is that of atoms and molecules.
Four main categories of biomolecules are proteins,
nucleic acids, carbohydrates, and lipids.
The charge on an amino acid residue is important and easily calculated.
0:39
In this second lecture,
you will learn that proteins are formed by the combination of 20 different amino acids.
The amino acids of protein polymers are linked by peptide bonds,
and you will see the hydrophobic effect,
key to understand how proteins fold.
Finally, in this lecture,
I will introduce you to a simple protein, myoglobin.
1:04
The form of ionisable groups at any pH is important.
Why is it important?
It's important for protein structure,
for protein binding with other molecules,
and for the very mechanism of catalysis.
On this slide, I will show you a chart that shows you
the pKa range found for amino acid residues in proteins.
Not the free amino acid,
but the amino acid when it's part of a protein.
So on the left, I'll show you ionisable groups in proteins.
First, any protein will have a terminal carboxyl group and a terminal amino group.
The convention I'll show you in this table is
if the ionisable group can have a negative charge,
you'll see this in red.
If the ionisable group can have a positive charge, you'll see blue.
So almost every protein has a terminal carboxyl group and it has a pKa,
not a precise value,
but there's a range of pKa's.
For a terminal carboxyl, about pH 3-4.6.
Why is it a range?
That is because the carboxyl group is not just found in water,
although it might be on the surface of proteins and in water,
that terminal carboxyl could be on the interior of
a protein and have a different environment that affects the pKa.
Similarly for the terminal amino group,
the terminal amino group can have a positive charge,
and the pKa range found in proteins is 7.2-8.2.
Then we'll look at the amino acid residues.
Aspartic and glutamic acids both have a carboxyl group.
For aspartic, the pKa range is 2.3- 4.7.
For glutamate, the pKa range is 3.3-5.1.
Histidine can have a positive charge for pH below the pKa.
The pKa range is in the physiological range, about 5.6-7.6.
The amino acid cysteine has an SH group.
That SH group can ionize and be negatively charged,
pKa range, about 4-9.
Tyrosine, an aromatic hydrocarbon,
that hydroxyl group has a pKa range 9.1-11.5.
The hydroxyl group can lose a proton and have a negative charge.
Then lysine and arginine both can have positive charges,
pKa range for lysine 9.4-11.6,
arginine, it's about 12.3.