Welcome to 3.091Lecture 31
November 30, 2009
Biochemistry: Protein Structure
(zwitterion)
Titration Curve for Alanine
Equivalents of OH
pH
2.01.51.00.500
2
4
6
8
10
12 pK2
pK1
pIAla
CH COO
COO
(anion)
CH3
CH3
CH
H2N
H3N
H H
H H
(cation)COOH
CH3
CHH3N
Image by MIT OpenCourseWare.
AMINO ACIDpKa VALUE
Carboxyl Group Amino Group Side Chain
Glycine
Alanine
Valine
Leucine
Isoleucine
Methionine
Proline
Phenylalanine
Tryptophan
Serine
Threonine
Cysteine
Tyrosine
Asparagine
Glutamine
Aspartic acid
Glutamic acid
Lysine
Arginine
Histidine
2.4
2.4
2.3
2.3
2.3
2.1
2.0
2.2
2.2
2.1
2.1
2.1
1.8
1.8
1.9
2.2
2.2
2.2
2.0
2.5
9.8
9.9
9.7
9.7
9.8
9.3
10.6
9.3
9.2
9.1
8.7
9.5
9.0
9.3
10.7
10.59.2
9.1
9.1
9.9
9.4
8.4
3.9
4.1
10.5
12.5
6.0
pKa values for constituents of free amino acids 25oCImage by MIT OpenCourseWare.
Courtesy of John Wiley & Sons. Used with permission. Source: Spencer, J. N.,G. M. Bodner, and L. H. Rickard. Chemistry: Structure and Dynamics.2nd edition, supplement.New York, NY: John Wiley & Sons, 2003.
Courtesy of John Wiley & Sons. Used with permission.
combinations of phenylalanine and aspartic acid (Phe) (Asp)© source unknown. All rights reserved.This content is excluded from our Creative Commons license.For more information, see http://ocw.mit.edu/fairuse.
data show that all six atoms lie in a plane
Image by MIT OpenCourseWare.
Image by MIT OpenCourseWare.
Image by MIT OpenCourseWare.
DNA alpha-helix
© Pearson/Prentice Hall. All rights reserved.This content is excluded from our CreativeCommons license. For more information,see http://ocw.mit.edu/fairuse.Source: Fig. 24.7 in McMurry & Fay.Chemistry, 4th ed. Prentice Hall, 2003.
Image by MIT OpenCourseWare.
DNA beta-pleated sheet.
© Pearson/Prentice Hall. All rights reserved.This content is excluded from our CreativeCommons license.For more information,see http://ocw.mit.edu/fairuse.Source: Fig. 24.8 in McMurry & Fay.Chemistry, 4th ed. Prentice Hall, 2003
© source unknown. All rights reserved. This content is excluded from ourCreative Commons license. For more information, see http://ocw.mit.edu/fairuse.
© source unknown. All rights reserved. This content is excluded fromour Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.
C
α - helix
β - sheet
Random coil
protein exhibiting various secondary structures
© source unknown. All rights reserved.This content is excluded from ourCreative Commons license.For more information,see http://ocw.mit.edu/fairuse.
tertiary structure of proteins
Underlying image © source unknown. All rights reserved. This content is excluded from ourCreative Commons license. For more information, see http://ocw.mit.edu/fairuse.
Courtesy of John Wiley & Sons. Used with permission.Source: Fig 8A.6 in Spencer, J. N.,G. M. Bodner, and L. H. Rickard.Chemistry: Structure and Dynamics.New York,NY: John Wiley & Sons, 2003.
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3.091SC Introduction to Solid State ChemistryFall 2009
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