Predicting the behaviour and selectivity of fluorescent probes for lysosomes and related structures by means of structure-activity models.
Cultured rat fibroblasts were exposed to 50 fluorescent probes of varied physicochemical characteristics. Probe concentrations, fluorochrome excitation wavelength and period of illumination, and cell-probe contact time were varied. Structure-activity relationships defining a number of classes of fluorescent probes for lysosomes and related processes and compartments were demonstrated. Numerical specifications are now available for several familiar classes of probes: (a) acidotropic weak bases, used as markers for low pH compartments; (b) markers of adsorptive pinocytosis, involving non-specific protein binding; (c) markers for fluid phase pinocytosis; and (d) viability stains involving intralysosomal enzymic activity. Two novel classes of probes have also been specified numerically: (a) acid-precipitated weak acids, as markers for low pH compartments; and (b) lipid-binding markers of adsorptive pinocytosis. Overall, these structure-activity models provide a tool for predicting whether or not compounds enter cells; and whether they accumulate in lysosomes and related compartments. Pathways of entry are also predicted. This tool should permit design and selection of improved probes, and provide a better understanding of existing reagents. Moreover these models are expected to be applicable to interactions between any non-polymeric xenobiotic with lysosomes and related compartments.
Rashid
F
F
Department of Biomedical Science, The University, Sheffield, UK.
Horobin
R W
RW
Williams
M A
MA
D000818:Animals; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D005456:Fluorescent Dyes / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship
D005456:Fluorescent Dyes