Difference between revisions of "Part:BBa K1080007"
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'''Usage and Biology '''
 
'''Usage and Biology '''
  
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A crucial regulatory step in the biosynthesis of chlorophyll in higher plants and algae is the reduction of protochlorophyllide to chlorophyllide. POR is unique in its formation as it directly utilizes light for catalysis.  POR is a major protein in the membrane of plants, without it, the chloroplasts would remain inactive. The protochlorophyllide absorbs light, excites the molecule and is reduced by NADPH to form chlorophyllide. The illumination of POR and its conversion of protochlorophyllide to chlorophyllide stops transforms etiolated membranes to active chloroplasts, which in turn provides energy once chlorophyll is produced.  
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A crucial regulatory step in the biosynthesis of chlorophyll in higher plants and algae is the reduction of protochlorophyllide to chlorophyllide. POR is unique in its formation as it directly utilizes light for catalysis.  POR is a major protein in the membrane of plants, without it, the chloroplasts would remain inactive. The protochlorophyllide absorbs light, excites the molecule and is reduced by NADPH to form chlorophyllide. The illumination of POR and its conversion of protochlorophyllide to chlorophyllide transforms etiolated membranes to active chloroplasts, which in turn provides energy to the plant once chlorophyll is produced.  
  
 
[[File:protochlorophyllide.png]]  
 
[[File:protochlorophyllide.png]]  

Revision as of 23:06, 14 October 2014

POR


Light-dependent protochlorophyllidereductase - Light-dependent protochlorophyllidereductase, chloroplast precursor; Converts protochlorophyllide to chlorophyllide using NADPH and light as the reductant; Chlamydomonas mutant known as pc-1 has a two-nucleotide deletion within the fourth and fifth codons of this gene giving rise to a premature termination [PMID: 8616232; identical to U36752]

Usage and Biology

A crucial regulatory step in the biosynthesis of chlorophyll in higher plants and algae is the reduction of protochlorophyllide to chlorophyllide. POR is unique in its formation as it directly utilizes light for catalysis. POR is a major protein in the membrane of plants, without it, the chloroplasts would remain inactive. The protochlorophyllide absorbs light, excites the molecule and is reduced by NADPH to form chlorophyllide. The illumination of POR and its conversion of protochlorophyllide to chlorophyllide transforms etiolated membranes to active chloroplasts, which in turn provides energy to the plant once chlorophyll is produced.

Protochlorophyllide.png

Figure 1: The reaction mechanism between POR and NADPH in the active site. (Reinbothe, Bakkouri et al. 2010)


Sequence and Features


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    INCOMPATIBLE WITH RFC[21]
    Illegal BglII site found at 600
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    INCOMPATIBLE WITH RFC[25]
    Illegal AgeI site found at 139
    Illegal AgeI site found at 190
  • 1000
    COMPATIBLE WITH RFC[1000]




Amino Acid Sequence
MVVCAATATA PSPSLADKFK PNAIARVPAT QQKQTAIITG ASSGLGLNAA KALAATGEWH
VVMACRDFLK AEQAAKKVGM PAGSYSILHL DLSSLESVRQ FVQNFKASGR RLDALVCNAA
VYLPTAKEPR FTADGFELSV GTNHLGHFLL TNLLLDDLKN APNKQPRCII VGSITGNTNT
LAGNVPPKAN LGDLSGLAAG VPAANPMMDG QEFNGAKAYK DSKVACMMTV RQMHQRFHDA
TGITFASLYP GCIAETGLFR EHVPLFKTLF PPFQKYITKG YVSEEEAGRR LAAVISDPKL
NKSGAYWSWS STTGSFDNK

Number of amino acids: 397

Molecular weight: 41871.0

Theoretical pI: 9.48

Amino acid composition:
Ala (A) 61 15.4%
Arg (R) 17 4.3%
Asn (N) 16 4.0%
Asp (D) 16 4.0%
Cys (C) 6 1.5%
Gln (Q) 14 3.5%
Glu (E) 13 3.3%
Gly (G) 27 6.8%
His (H) 7 1.8%
Ile (I) 12 3.0%
Leu (L) 36 9.1%
Lys (K) 25 6.3%
Met (M) 10 2.5%
Phe (F) 15 3.8%
Pro (P) 22 5.5%
Ser (S) 37 9.3%
Thr (T) 24 6.0%
Trp (W) 4 1.0%
Tyr (Y) 7 1.8%
Val (V) 28 7.1%
Pyl (O) 0 0.0%
Sec (U) 0 0.0%

(B)   0	  0.0%
(Z)   0	  0.0%
(X)   0	  0.0%


Total number of negatively charged residues (Asp + Glu): 29 Total number of positively charged residues (Arg + Lys): 42

Atomic composition:

Carbon C 1849 Hydrogen H 2965 Nitrogen N 521 Oxygen O 554 Sulfur S 16

Formula: C1849H2965N521O554S16 Total number of atoms: 5905

Extinction coefficients:

Extinction coefficients are in units of M-1 cm-1, at 280 nm measured in water.

Ext. coefficient 32805 Abs 0.1% (=1 g/l) 0.783, assuming all pairs of Cys residues form cystines


Ext. coefficient 32430 Abs 0.1% (=1 g/l) 0.775, assuming all Cys residues are reduced

Estimated half-life:

The N-terminal of the sequence considered is M (Met).

The estimated half-life is: 30 hours (mammalian reticulocytes, in vitro). 

                           >20 hours (yeast, in vivo).
                           >10 hours (Escherichia coli, in vivo).


Instability index:

The instability index (II) is computed to be 36.61 This classifies the protein as stable.


Aliphatic index: 82.97

Grand average of hydropathicity (GRAVY): -0.035


Source

Chlamydomonas reinhardtii