welcome to 3(zwitterion) titration curve for alanine equivalents of oh ph 0 0.5 1.0 1.5 2.0 0 2 4 6...

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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