Molecular Surfaces Using IsoSurfaces

Python Prescription - Virtual Screening Tool

[PyRx is no longer developed at MGL]

Moderator: sargis

Forum rules
[PyRx is no longer developed at MGL]

Molecular Surfaces Using IsoSurfaces

Postby sargis » Thu Jun 04, 2009 6:11 pm

There are a number of programmes for computing Molecular Surfaces; MSMS being one of the best that I use regularly in MGLTools. However, for PyRx, I needed something with permissive free software licence, and since, as far as I know, there is none available, I decided to write one myself. I remember reading A General Mesh Generation Tool for Finite Element Analysis of Bio-Structures; so I just needed to code the first formula from this article, with blobbyness parameter, and use IsoSurface Module from MayaVi, which provides convenient access to appropriate functionality in VTK. Here is the complete code:
Code: Select all
    def DisplayMolecularSurface(self, molecule):
        bloby = -1
        spacing = 10       
        bounds = molecule.assembly.GetBounds()
        dimX = int(abs(bounds[1]-bounds[0])) + spacing
        dimY = int(abs(bounds[3]-bounds[2])) + spacing
        dimZ = int(abs(bounds[5]-bounds[4])) + spacing
        origX =   int(bounds[0]) - spacing/2
        origY =   int(bounds[2]) - spacing/2
        origZ =   int(bounds[4]) - spacing/2               
        img = tvtk.tvtk.tvtk.ImageData(origin=[origX,origY,origZ], spacing=[1,1,1], dimensions=[dimX, dimY, dimZ] )
        scalars = zeros((dimX, dimY, dimZ))
        for atom in molecule.allAtoms:
            coords = atom._coords[0]
            intX = int(coords[0])
            intY = int(coords[1])
            intZ = int(coords[2])
            iX = int(abs(origX - coords[0]))
            iY = int(abs(origY - coords[1]))
            iZ = int(abs(origZ - coords[2]))
            p = 2
            for i in range(-p, p+1):               
                for j in range(-p, p+1):
                    for k in range(-p, p+1):                                   
                        e = (intX + i- coords[0])*(intX + i - coords[0]) +\
                               (intY + j - coords[1])*(intY + j - coords[1])+\
                               (intZ +k - coords[2])*(intZ +k - coords[2])                   
                        scalars[iX+i, iY+j, iZ+k] += math.exp(bloby*(e/(atom.vdwRadius*atom.vdwRadius)-1))
        s = scalars.transpose().copy()
        img.point_data.scalars = ravel(s) =
        src = VTKDataSource(data=img,"-grid")
        mayavi = self.engine
        iso = IsoSurface()

I committed this code to CVS under PyRxDIST/PyRx/
Molecular Surfaces computed in PyRx.
snapshot.png (132.4 KiB) Viewed 5508 times
User avatar
Picomolar User
Picomolar User
Posts: 583
Joined: Fri Oct 17, 2008 10:39 pm

Return to PyRx

Who is online

Users browsing this forum: No registered users and 1 guest