Words similar to protoporphyrin
Example sentences for: protoporphyrin
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Porphyrin designations are as follows: PP, protoporphyrin IX; HP, hematoporphyrin IX; TPP, meso -tetraphenylporphine; TNapPS, sulfonated 5,10,15,20-tetra-naphthalen-1-yl-porphyrin; TAnthPS, sulfonated 5,10,15,20-tetra-anthracen-9-yl-porphyrin.
, hydroxyethyl groups at the 2- and 4-positions, see CuHPIX in Figure 1) were found to be more active than structures with the protoporphyrin (see ZnPPIX in Figure 1), mesoporphyrin, deuteroporphyrin or deuteroporphyrin disulfonic acid rings (ethyl, hydrogen or sulfonate at positions 2 and 4, respectively).
This basic domain organization shows a striking parallel to that of magnesium chelatase, a heterotrimeric enzyme containing BchD, BchI and BchH subunits, that performs ATP-dependent insertion of Mg 2+into the protoporphyrin IX ring in the course of chlorophyll biosynthesis [ 49 ] . In particular, the BchD subunit resembles midasin in possessing a single AAA protomer close to its NH 2 -terminus, together with a short aspartate-glutamate-rich region and a MIDAS-containing domain at its carboxy-terminus.
The BchI subunit also possesses a single AAA protomer, but contains no MIDAS domain [ 32 ] . The third subunit BchH is able to bind the protoporphyrin ring in either the presence or absence of ATP.
The initial step of the insertion can proceed in the presence of either Mg.ATP or a non-hydrolyzable ATP-analog and involves oligomerization of the BchD and BchI subunits to form an oligomeric ring of AAA protomers that resembles the ring structure of NSF and other AAA proteins [ 14 32 ] . The second step of the insertion involves an obligatory hydrolysis of ATP that is tightly coupled with the transfer of the chelated Mg 2+to the protoporphyrin ring by BchH [ 49 ] . Although the details differ from midasin, particularly with respect to the subunit composition of the AAA ring, this chelation reaction provides a structural model suggesting that the function of the midasin M-domain may be to regulate the ATPase activity of the AAA protomers in the pseudo-hexameric ring and thus couple ATP hydrolysis to the binding of a protein ligand at the MIDAS site.
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