Biomedical Engineering Reference
In-Depth Information
subunits results in a quaternary structure. The forces between polypeptide chains can be
disulfide bonds or other weak interactions. The subunit structure of enzymes has an
important role in the control of their catalytic activity.
Antibodies or immunoglobulins are proteins that bind to particular molecules or portions of
large molecules with a high degree of specificity. Antibody (Ab) molecules appear in the
Phe
Glu
Arg
Gln
His
Met
Asp
Ser
Ser
Lys
Ala
Ala
Ala
Thr
Thr
Ser
Arg
Ser
Arg
Glu
Lys
Ser
Ser
Asn
1
Tyr
Cys
Asn
26
Ser
Tyr
Thr
Ser
Met
Ser
Gln
Ile
Thr
Tyr
Asp
Lys
Met
Cys
84
Cys
72
Ser
Met
Gln
Arg
Arg
Asn
Leu
Thr
Lys
Asp
Arg
Cys
Asn
Cys
65
Glu
Thr
Ser
Ser
Lys
Asn
Thr
Gly
Ala
Gln
Lys
Tyr
Pro
Asn
Cys
Gly
Val
Ser
Ala
Asp
His
Val
Pro
Tyr
Pro
Phe
Val
Asn
Val
Asn
Gly
124
Lys
Glu
95
110
Gln
Cys
Ser
Ala
Ala
Cys
58
40
Tyr
Val
Ile
Val
Lys
Pro
Val
Lys
Ile
Thr
Asn
Lys
His
Ala
Thr
Gln
Ala
Gln
Val
Asn
Asp
Thr
Phe
Val
Glu
Ser
Leu
Ala
His
(a)
Primary amino acid sequence, showing how sulfur-sulfur bonds between cysteine residues
cause folding of the chain.
1
65
40
72
Active site
95
110
58
84
124
26
a site of enzymatic activity is formed, the active site.
FIGURE 2.15
Structure of the enzyme ribonuclease. (a) Primary amino acid sequence, showing how sulfur
e
sulfur bonds between cysteine residues cause folding of the chain. (b) The three-dimensional structure of ribonu-
clease, showing how the macromolecule folds so that a site of enzymatic activity is formed, the active site.
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