In banana, ripening is characterized by a climacteric rise in

respiration rate, as evidenced by the increased CO2 production.

A climacteric rise in ethylene production precedes the increase in CO2 production, suggesting that ethylene is the hormone that triggers the ripening process.

#Id: 7688

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                       Zinc Finger Motif

Zinc atom stabilizes the structure/fold by coordination bonds

Each motif contains about 30-50 amino acids

Contains regular patterns of Cys / His, which coordinate with Zinc atom

Contains one helix and two small anti-parallel beta sheets in each finger

Zinc holds helix and beta-sheets together

Helix binds to DNA

#Id: 7689

#Unit 1. Molecules and their Interaction Relevant to Biology

                                         Zinc Finger Motif

 


#Id: 7690

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                                  bab Motif

Two beta strands are connected by a long region containing a helix

These beta strands form parallel beta-sheets

The loop regions connecting sheet and helix can have different length

The helix axis is generally parallel to beta-sheets

Three secondary structures are stabilized by hydrophobic interactions


#Id: 7691

#Unit 1. Molecules and their Interaction Relevant to Biology

                                             bab Motif

These motifs are generally found in right handed helix above the plane of the beta sheet

Almost all the proteins containing parallel beta sheets have this motif. 

The helix is generally not seen below the plane of beta sheets                                           

#Id: 7692

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                  bab Motif

#Id: 7693

#Unit 1. Molecules and their Interaction Relevant to Biology

                                                           aa motif / Coiled-coils

Two helices are wound around each other

Alpha-helices are packed together through the hydrophobic interactions

These two helices are found to be stable in solution

They are generally found in transcription factors and intermediate filaments

They have heptad (7 amino acid) repeated sequences