CHEMISTRY 102
CHEMISTRY 102
BIOCHEMISTRY SUPPLEMENT C




                     Amines & Amides

1.   You should be able to define and/or 
     identify the following terms:

     primary amine		biological activity 
     secondary amine		primary structure 
     tertiary amine		secondary structure
     amide			alpha-helix
     alpha-amino acid		beta-structure
     peptide bond		tertiary structure
     N-terminal			quaternary structure
     C-terminal			subunit
     isoelectric point		conjugated
     peptide			denaturation
     protein			enzyme
     



2.   You should be able to differentiate between the structures of
     primary, secondary and tertiary amines.

3.   You should be able to write formulas for amines and amides
     when given the names and vice-versa.

4.   You should be able to describe the general properties of amines
     in terms of their structure.

5.   You should be able to write equations for the preparation of
     amides from amines.

6.   You should be able to 

     a) write equations for the reactions of amines with acids and 

     b) describe the solubility of the product in water.

7.   You should be able to determine whether an amino acid is
     "neutral", "basic" or "acidic" when given the structure.

8.   You should be able to explain the unusual physical properties of
     amino acids in terms of their structure and "dipolar" nature.

9.   You should be able to show how a peptide bond forms between amino
     acids.

10.  You should be able to describe the type of bonding responsible
     for the primary, secondary, and tertiary structure of protein.

11.  You should be able to explain how the amino acid sequence is
     determined for a protein.

12.  You should be able to describe the action of an enzyme.



                         AMINES AND AMIDES             

1.   Classification of Amines:

     Comparison: C:  primary     C attached to one other C
                     secondary   C attached to two other C's
                     tertiary    C attached to three other C's
                     quaternary  C attached to four other C's

     But for amines look at C's attached to N:

     [CH3NH2]       primary  amine:  N attached to one C

     [(CH3)2NH]   secondary  amine:  N attached to two C's

     [(CH3)3N]     tertiary  amine:  N attached to three C's

     and there is a quaternary N ion, with N attached to four C's;

     example:  N(CH3)4+

     (These are called quaternary ammonium ions.)


2.   Preparation of Amines:

     a.   Alkyl halides + NH3:

          CH3CH2Cl  +  NH3     CH3CH2NH2  +  HCl
                                        
                             primary amine 
                                        

     b.   Alkyl halide + amines:

          1)   CH3CH2Cl  +  CH3CH2NH2     CH3CH2-N-H  +  HCl
                                                 | 
                                                 CH2CH3
                                                            
                                            secondary amine 
                                                            
          2)  CH3CH2Cl  +  CH3CH2-N-H     CH3CH2-N-CH2CH3
                                  |              |     
                                  CH2CH3         CH2CH3 + HCl
                                                              
                                             tertiary amine 
                                                              

3.   Preparation of Amides:

     a.   Unsubstituted:  *RCOOH + NH3,  :  (review!)

             O                     O
             "                     " 
          CH3COH  +  NH3 -----> CH3CNH2  +  H2O
                            

     b.   Substituted:  *RCOOH  +  R'NH2,  

          1)      O                        O
                  "                        " 
               CH3COH  +  CH3NH2-----> CH3CNHCH3  +  H2O
                                    

          2)      O                          O
                  "                          "  
               CH3COH  +  (CH3)2NH -----> CH3CN(CH3)2  +  H2O
                                      

          NOTE:  only primary amines and 
                      secondary amines form amides
                                               
                     O                         
                     "                          
          *RCOOH or RCCl  react the same way.  
                                               
4.   Reactions:

     a.   Amines are bases:  RNH2 + HCl react.

          CH3NH2  +  HCl     CH3NH3+ + Cl-

                              salt (solubility increases)

     b.   Formation of Amides:  See #3 above.

5.   Names:

     a.   Common names for amines:

          (CH3)3N        trimethylamine

     b.   Substituted amides:

             O
             " 
          CH3CN(CH3)2    N,N-dimethylethanamide



                             PRACTICE SET                

                            Amines, Amides


1.   Draw a structure for each of the following:

     a.   isopropylamine

     b.   isobutylmethylamine

     c.   ethylmethyl-n-propylamine

2.   Classify each of the amines in 1. above as 
     primary, secondary or tertiary.

3.   Complete the following reactions with the 
     organic product:

     a.   CH3CH2CH2NH2  +  HI   

     b.        N-CH3  +  HCl   
               | 
               CH3


4.   Complete the following hydrolysis reactions:

     a.            O
                   " 
          CH3CH2CH2CNH2  +  H2O ----->
                                  H+

     b.            O
                   " 
          CH3CH2CH2C-N-CH3  +  H2O ----->
                                     H+
                     CH2CH3




                       PRACTICE SET ANSWERS           

                            Amines, Amides


1.   a.   CH3CHCH3            isopropylamine
             | 
             NH2

     b.              CH3
                     | 
          CH3-N-CH2CHCH3    isobutylmethylamine
              |  
              H

     c.   CH3-N-CH2CH3      ethylmethyl-n-propylamine
              |  
              CH2CH2CH3

2.   a.   primary amine
     b.   secondary amine   in 1. above
     c.   tertiary amine  

3.   a.   CH3CH2CH2NH2 + HI   CH3CH2CH2NH3+I-

     b.                                   H+ 
                                          |
           CH3-N-CH3  +  HCl  ----->  CH3-N-CH3  +  Cl -
               |                          |
               C                          C
              / \			 / \
           H-C   C-H		      H-C   C-H
             |O|	               |O|           
           H-C   C-H		      H-C   C-H
              \ /			 \ /
               C			  C	
               |			  |	
               H			  H	




                 H H
                 | |
                 C-C   CH3
                /   \  |
             H-C O C-N   + HCl  ----->                
                \   /  | 
                 C-C   CH3
                 | |
                 H H



                 H H
                 | |   
                 C-C   CH3
                /   \  |  +      -
             H-C O C-N-H   + Cl                
                \   /  | 
                 C-C   CH3
                 | |
                 H H



 
4.   a.       O                         O                    O
              "            H+           "                    "   
     CH3CH2CH2CNH2 + H2O ----> CH3CH2CH2COH + NH3   CH3CH2CH2CO-  NH4+
                                                   

     b.            O                                 O
                   "                  H+             "  
          CH3CH2CH2C-N-CH2CH3 + H2 ------> CH3CH2CH2COH  +  NHCH2CH3
                                                            |  
                     CH3                                    CH3
							    
							    ||	
							    ||                                                         
                                                            ||  H+
                                                            ||  
							    ||
							    \/
	
                                                            H
                                                            | +
                                                          H-N-CH2CH3
                                                            |  
                                                            CH3



                       Amino Acids and Proteins

                                                            O
                                                            " 
1.    -Amino acids are the only ones we will focus on. -N-C-C-OH
                                                           
                                                           

2.   Description of a protein includes

     PRIMARY    - amino acid sequence (amides; covalent bonds)
     SECONDARY  - alpha-helix or -pleats (H-bonding; polar forces)
     TERTIARY   - coiling, bending and folding into 3-D shape 
     and 
     QUATERNARY - aggregation of biologically active sub-units.

     Not all proteins have a tertiary or quaternary 
     structure.  Hemoglobin, a globular protein, does.

3.   The primary structure is very important to the protein.  Any change in
     amino acid sequence changes the protein.  Example:  sickle cell
     anemia

4.   Denaturing proteins:  irreversible destruction of all but primary
     structure.  

     Heat; pH; solvents; agitation; heavy metals, etc.

5.   Enzymes:  wholly or in part proteins, that act as biological
     catalysts





                             PRACTICE SET           

                       Amino Acids and Proteins

12.  Define the following terms:

     a.   tripeptide

     b.   isoelectric point

     c.   N-terminal

     d.   C-terminal

13.  Identify the peptide (amide) linkages in the following structure:

             O
             "  
     H2N-C-C-N
         |  
         CH3              
                            O
                         C
                                        O       O
                            NH__CH__C            
                                        NH__CH__C__OH
                                CH2          
                                            CH2
                                OH           
                                            C=O
                                             
                                            OH

14.  List and describe the types of forces that determine the tertiary
     structure of a protein.

15.  Distinguish between the 1 , 2 , 3  and 4  structures of a
     protein.

                                ANSWERS

12.  a.   tripeptide:  a polymer consisting of three amino acids
          linked as amides.

                 O  R  R'  O  R" R   O
                                      
          R__CH__C__N__CH__C__N__CH__C__OH
              
             NH2

     b.   isoelectric point:  the pH at which an amino acid exists in
          its dipolar form.
                    O         
          R__CH__C
                    O-
             NH3+

     c.   N-terminal end of a peptide:  the end with the free amino
          group.

     d.   C-terminal end of a peptide:  the end with the free carboxyl
          group.

13.           O
               
     H2N__CH__C__N
           
          CH3
     alanine                O
     ala                 C
                                        O       O
                            NH__CH__C            
               proline                  NH__CH__C__OH
               pro              CH2          
                                            CH2
                                OH           
                                            C=O
                         serine              
                         ser                OH

                                            aspartic acid
                                                asp
     ala pro ser asp sequence

14.  The tertiary structure of a protein refers to the coiling and
     bending of the helix.  One type of force which is responsible for
     the coiling and bending is the "salt bridge" linkage, the
     attraction of two oppositely charged groups such as -NH3 + and
      O
       
     -C-O -
     Hydroxy side groups will align towards water because of H-bond. 
     S-S linkages form from S-H groups.  In general, the protein will
     coil with non-polar groups to the center and polar groups to the
     outside.

15.  Primary structure of proteins:  sequence of amino acids in the
     peptide.

     Secondary structure of proteins:  the  -helix with H-bonding
     between coils.

     Tertiary structure of proteins:  the twisting, bending and
     coiling of the  -helices due to ionic attractions, H-bonding.

     Quaternary structure of proteins:  large superstructures
     resulting from the aggregation of subunits made up of the coiled,
     bent  alpha-helices.

        
  

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