Tobacco Mosaic Virus as a Carrier for Small Molecules I. The preparation and characterization of a TMV/α‐melanotropin conjugate

Abstract

SummaryThe use of tobacco mosaic virus (TMV) covalently loaded with hormones or other small molecules for various purposes including receptor detection and isolation is proposed. The basic principle is that of cooperative affinity interactions involving (large) numbers of artificially introduced sites (e.g. hormones) of the modified virus on the one hand and membrane-bound sites (e.g. receptors) of a cell or of a cellmembrane particle on the other. In order to test the feasibility of such TMV/hormone conjugates, TMV carrying about 500 molecules of a biologically active a -melanotropin analogue was synthesized, and characterized by its aspect under the electron microscope, by its infectivity, its melanophore-stimulating activity, and its reaction with antisera against a -melanotropin. The observed hormonal activity is in accordance with the idea of cooperative affinity interactions.The chemical nature of membrane-bound receptors for drugs and hormones is still an unsolved problem of molecular biology. This paper is the first of a series investigating the use of tobacco mosaic virus (TMV) covalently attached to hormones, drugs, and other comparatively small molecules for the study of receptors. First, some pertinent chemical properties of TMV and of polypeptide-hormone receptors are reviewed and the concept of cooperative affinity labelling is introduced. It is then demonstrated that some 500 molecules of an a-melanotropin (a-MSH) analogue can be covalently attached to the virus particle without destroying the essential chemical and biological properties characteristic of the virus and the hormone. I )This work was supported by the Swiss National Science Foundation. Abbreviations: TMV= tobacco mosaic virus; EM. = electron microscopy; symbols for amino acids and peptides according to the IUPAC-IUB rules [ 11.

Bench-top to clinical therapies: A review of melanocortin ligands from 1954 to 2016

“…Eberle et al . coupled α-MSH peptides (six to several hundred) to albumin, thyroglobulin, and tobacco mosaic virus which resulted in 1500-fold higher potency than α-MSH alone [218, 219]. Bivalent ligands were first reported in the clinic by Barb et al .…”

Tobacco Mosaic Virus as a Carrier for Small Molecules. II. Cooperative affinity labeling of membrane vesicles with a TMV angiotensin conjugate. Preliminary communication

“…The idea of cooperative affinity labeling was introduced in the preceding paper [ 2 ] . There, an unexpectedly strong melanophore-stimulating activity of a TMV a-melanotropin (500)4) conjugate was demonstrated, for which cooperativity is a possible explanation.…”

“…Gel-electrophoresis at pH 6.8 showed that a certain amount of non-covalently bound ANG' was associated with the TMV. Electrodialysis [2] at pH 4.5 removed the excess ANG': 635 ANG' molecules remained (covalently) bound to the virus; however, the TMV particles were strongly damaged and degraded to RNA and capsomers as shown by EM. and by CsCl gradient centrifugation.…”

“…in CDCI, indicated both purity and identity. (3-Mercapto-1-succiny1)-TMV (TMV-SH) was synthesized as described [2] and the number of introduced mercapto groups assayed by the Ellman DTNB reagent [7] as about 600 per TMV particle. A ten-fold excess of ANG' over TMV-SH was dissolved in a small volume of glacial acetic acid/ methanol and its apparent pH adjusted to 3.0 with dilute NaOH-solution.…”

Evaluation of novel 99mTc(I)-labeled homobivalent α-melanocyte-stimulating hormone analogs for melanocortin-1 receptor targeting

“…The first examples of a-MSH multivalent constructs consisted of several a-MSH molecules coupled to albumin, thyroglobulin, and tobacco mosaic virus, which displayed a 1,500-fold higher potency than a-MSH alone [32,33]. Further structure-bioactivity studies have demonstrated that enhanced binding affinity could also be achieved with bivalent constructs [34,35].…”