a gene of the vp1 coat protein of the murine polyoma virus is taken which contains sequence features of both the strain a2 and the strain a3 . the coding sequence beginning with the atg or the following amino acid is cloned immediately behind a factor xa cleavage site in a derivative of the commercially available vector pqe 10 from quiagen . this vector provides the fusion protein xa cleavage site vp1 at the amino terminus with a histidine sequence . the fusion construction thus obtained is cloned inside a marker gene ( lacz complementation ) and is inducible via the lacz promoter . the final construction is transformed in e . coli cells suitable for the expression of pqe vectors . when the cells , after prior culture , are in the logarithmic phase , they are induced by addition of a suitable inductor , e . g . iptg . after this , they express large amounts of a fusion protein containing the vp1 protein . the fusion protein is harvested after induction for 6 hours . it is present in soluble form and can be prepared pure on nickel chelate columns with minor changes to the purification protocol of quiagen . by incubation with factor xa , the pure vp1 protein portion of the fusion protein can be removed again from the nickel chelate column . the vp1 protein obtained is present in very pure form and forms pentamers by itself . the proteins vp2 and vp3 can be prepared analogously . fig1 shows the gel electrophoretic detection of the vp3 , vp2 and vp1 fusion proteins . shown in fig2 are on the left an electron microscopic view of pentamers formed from the vp1 protein and on the right a computer - assisted illustration of the 5 - fold symmetry of the pentamers . 2 ) modification of the cysteine residues on one side of the pentamers before their assembly the vp1 pentamers obtained according to example 1 above have a plurality of structures which can be converted into bifunctional groups by reaction with suitable reagents . the structures are found on the side of the pentamers which corresponds to its inside after assembly to give the capsid . the reagent used is a 3 - maleimidobenzoyl - n - hydroxysuccinimide ester dispersed in an acetone / methanol / water mixture , which on one side of the reactive center carries as reactive groups sh groups and on the other side a reactive ester group , namely an amino group - reactive succinimide ester . the dispersion is mixed with the dissolved vp1 proteins so that a quantitative reaction takes place . shown in table 1 are the loop structures of polyoma capsomeres which are to be found on one side of the capsomeres and which after assembly point to the inside of the capsid or the capsid - like structure : loop 1 : asp 38 , leu 39 , val 40 , thr 41 , gly 42 , pro 43 , asp 44 , ser 45 loop 2 : asn 109 , glu 110 , asp 111 , leu 112 , thr 113 , lys 114 , asp 115 , thr 116 , leu 117 tail : n - terminus of amino acid residue 1 to residue 29 ( at least from the amino acid 18 of the n - terminus which is well localized in the structural analysis up to residue 29 ): lys 18 , ala 19 , cys 20 , pro 21 , arg 22 , pro 23 , ala 24 , pro 25 , val 26 , pro 27 , lys 28 , leu 29 loop 3 : tyr 354 , asp 355 , gly 356 , thr 357 , gln 358 , pro 359 , val 360 the vp1 pentamers are present in a buffer solution which contains egta to stabilize the pentameric non - assembled state . magnesium ions , sodium ions and tris / hcl , ph 7 . 6 , are further added to the buffer solution to stabilize the ph . the protein solution is transferred to a dialysis chamber and dialyzed against a 2m ammonium sulfate solution . after several changes of the dialysis buffer , the vp1 pentamers form capsids . these do not differ from empty capsids of the polyoma virus on inspection in the electron microscope , in diameter , or in their stability , although they lack the inner coat proteins vp2 and vp3 . fig3 a through 3c shows the pentamers prepared and capsids formed therefrom . conventional oligonucleotides , i . e . those unchanged in their chemical structure , can be packed into polyoma vp1 capsids in high yield according to the following protocol : capsid structures , such as have been obtained in example 3 , are buffered to ph 5 . 5 . they are then reacted in an osmotic shock procedure with an equi - or higher molar amount , typically with a two - fold molar excess , of oligonucleotides . for the oligonucleotides used in this example ( 20 - mers ) a weight ratio of about 1 : 6 thus results compared with the vp1 protein . the form of the vp1 capsids loaded with oligonucleotides thus obtained cannot be differentiated in the electron microscope from the unloaded vp1 capsids . fig4 shows an electron microscopic view of loaded vp1 capsids .
the invention relates to a vehicle for the transport of molecular substance , such as dna , rna , protein , pna , pharmaceuticals of lipophilic and lipophobic character , into eukaryotic cells comprising at least one capsomere derived or originating from a virus , which on one of its sides interacts with the molecular substance such that the molecular substance can be bound or added to the capsomere .