Amazing Pokeweed
Mon, 15 Aug 2005 07:24:01 PDT
In a message dated 8/14/2005 10:55:18 P.M. Eastern Standard Time,  writes:
>            Phytolacca americana is not grown in most of Botanic gardens 
>because  years ago it was discovered that is capable of carrying most 
>that affect garden plants WITHOUT SHOWING SYMPTOMS.

===>I didn't know this and Alberto's posting prompted me to look a  little 
further into pokeweed. I found one abstract, quoted below, that indicates  
pokeweed may also be helpful in HIV cases. It appears to be a most complex  plant.

Bill Lee

The Biotherapy and Drug Discovery Program, Parker  Hughes Cancer Center, 2699 
Patton Road, St. Paul, MN 55113, USA.

Pokeweed  antiviral protein III (PAP-III), a naturally occurring protein 
isolated from  late summer leaves of the pokeweed plant (Phytolacca americana), 
has potent  anti-HIV activity by an as yet undetermined molecular mechanism. 
PAP-III belongs  to a family of ribosome-inactivating proteins that catalytically 
deadenylate  ribosomal and viral RNA. The chemical modification of PAP-III by 
reductive  methylation of its lysine residues significantly improved the 
crystal quality  for X-ray diffraction studies. Trigonal crystals of the modified 
PAP-III, with  unit cell parameters a=b=80.47A, c=76.21A, were obtained using 
30% PEG400 as the  precipitant. These crystals contained one enzyme molecule 
per asymmetric unit  and diffracted up to 1.5A, when exposed to a synchrotron 
source. Here we report  the X-ray crystal structure of PAP-III at 1.6A 
resolution, which was solved by  molecular replacement using the homology model of 
PAP-III as a search model. The  fold typical of other ribosome-inactivating 
proteins is conserved, despite  several differences on the surface and in the loop 
regions. Residues Tyr(69),  Tyr(117), Glu(172), and Arg(175) are expected to 
define the active site of  PAP-III. Molecular modeling studies of the 
interactions of PAP-III and PAP-I  with a single-stranded RNA heptamer predicted a more 
potent anti-HIV activity  for PAP-III due to its unique surface topology and 
more favorable charge  distribution in its 20A-long RNA binding active center 
cleft. In accordance with  the predictions of the modeling studies, PAP-III 
was more potent than PAP-I in  depurinating HIV-1 RNA.

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