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pst
PstI is a type II restriction endonuclease isolated from the Gram negative species, Providencia stuartii. It is the isoschizomer of Streptomyces albus P restriction enzyme SalPI. It cleaves DNA at the recognition sequence 5′-CTGCA/G-3′ generating fragments with 3′-cohesive termini. This cleavage yields sticky ends 4 base pairs long. PstI is catalytically active as a dimer. The two subunits are related by a 2-fold symmetry axis which in the complex with the substrate coincides with the dyad axis of the recognition sequence. It has a molecular weight of 69,500 and contains 54 positive and 41 negatively charged residues.
The PstI restriction/modification (R/M) system has two components: a restriction enzyme that cleaves foreign DNA, and a methyltransferase which protect native DNA strands via histone methylation. The combination of both provide a defense mechanism against invading viruses. The methyltransferase and endonuclease are encoded as two separate proteins and act independently. In the PstI system, the genes are encoded on opposite strands and hence must be transcribed divergently from separate promoters. The transcription initiation sites are separated by only 70 base pairs. A delay in the expression of the endonuclease relative to methylase is due to the inherent differences of the two proteins. The endonuclease is a dimer, requiring a second step for assembly, whereas the methylase is a monomer.
PstI is functionally equivalent to BsuBI. Both enzymes recognize the target sequence 5'CTGCAG. The enzyme systems have similar methyltransferases (41% amino acid identity), restriction endonucleases (46% amino acid identity), and genetic makeup (58% nucleotide identity). These observations suggest a shared evolutionary history.
When examining the preferential double strand cleavage of DNA, the restriction endonuclease PstI bind to pSM1 plasmid DNA.
*******SOLD********
For sale- Hillsboro Oregon- Willing to ship
Vortex gen 1 PST 4-16x50 MOA FFP, original box and everything included in it. Used but not abused! Will add more pictures with interest and I’ll take it off my rifle. Only reason I’m selling is to fund new optic. Great glass
ALSO...
New in Box Vortex Viper PST 1-4 x 24. Has the TMCQ reticle (MOA). Model #PST-14ST-A. Still sealed in the package. I bought this with the intention of using it for three-gun competition but never had a chance to compete.
MSRP was $649. Cheapest on Amazon or Ebay I can find it is $595 +...
We will be performing another round of site maintenance tonight at midnight. If all goes well downtime will be minimal, estimated to be 30 minutes or less. Apologies for the inconvenience.
Thanks,
Joe Link
I have a like new Gen2 Vortex Viper PST 5-25x50 Front Focal Plane MRAD ebr-2c Scope with Vortex Switchview Throw Lever and Bubble Level. MIL/MIL Turrets/Reticle. Comes with Box and usual contents from the factory, Flip-up Caps, Sunshade, etc...
LINK: Vortex Optics - Viper PST Gen II 5-25x50...
For Sale:
Like new Vortex Viper PST Gen 2 5x25x50mm FFP, MRAD EBR-2c. Comes with the Vortex SV5 throw lever and Flatline Ops Recon 30mm level. Comes with original box and all the goodies (including Vortex decal).
$1000
Location: Tacoma, WA
Willing to ship at buyers expense, PayPal preferred...
Upgrading to razor so this one has to go. Only mounted once and about 150 rds on a 6.5 Creedmoor. Box, manual, sun shade and shims included.
Seekins high rings included.
$600
Sorry no trades. Cash only.
Possibly interested in parting ways with my like new Gen 1 6-24x50 Vortex PST Viper that currently sits on my Tikka. This scope features the illuminated EBR-1 MRAD FFP reticle. Included is a brand new Vortex 30mm cantilever mount, new Vortex SV-2 throw lever, new Vortex bubble level and a set of...
SOLD
Asking $900 for scope and accessories.
Scope comes with accessories:
Front and rear Vortex defender caps
Vortex Precision matched rings 30mm - Height 0.87 IN
Vortex SV-2 throw lever
Vortex Optics - Viper PST 6-24x50 FFP EBR-2C<br />(MRAD)
We will be performing site maintenance tomorrow morning beginning at 4am. If all goes well downtime will be minimal. We don't have an estimated time of completion, but we're hoping to wrap things up within a two hour period. Apologies for the inconvenience.
Thanks,
Joe Link
Viper PST 1-4. Like new condition, only sign of use is a very small nick on the illumination cap. Includes original box and everything that comes with when new. $350 firm.
AD Recon 30 STD mount. Like new, includes original box/wrench/manual. $100 WITH PURCHASE of PST, will not sell seperate...
Vortex viper PST 1-4×24 mil/mil has throw lever and comes with rings. In great shape and of course the vortex warranty. Asking 425 plus shipping if needed.
Trade for eotech exps2-0 or -2
The site will be going down for some emergency maintenance tonight at midnight. We don't have an estimated time of completion, but we're hoping it'll be a matter of minutes versus hours. Apologies for the inconvenience.
Thanks,
Joe Link
I'm selling my Viper PST to fund another scope. This is the first focal plane version with mil/mil, turrets and reticle. Everyone knows how great these scopes are so I won't go into detail unless you're seriously interested and have questions. This scope does have some scuffs on the bottom...
I have brand new. Mounted but never fired with Vortex Viper PST 6-24x50 FFP EBR-2C MRAD Scope. I paid 1k for it from Sport Optics back then. Currently sitting on my unfired PRS Rifle in Vortex Precision Matched Rings 0.97. Have everything that it came with. Will let it go for $700 including...