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Auxin-binding proteins (ABP) were identified in plasma membrane of maize coleoptile tissue to study auxin metabolism during plant growth. Several indole3-acetic acid (IAA) binding proteins with different molecular masses were identified by photoaffinity labeling technique. One IAA-binding protein with a molecular mass of 23 kiloDalton (kDa) (pm23) was purified to homogeneity and was found to be similar with ABP protein 1. A 24kDa (pm24) ABP was also found in the microsomal vesicle preparation and a simultaneous purification techniquewas developed for both IAA-binding proteins.

²H magnetic resonance spectroscopic imaging has been shown recently to be a viable technique for metabolic imaging in the clinic. We show here that ²H MR spectroscopy and spectroscopic imaging measurements of [2,3-²H2]malate production from [2,3-²H2]fumarate can be used to detect tumor cell death in vivo via the production of labeled malate. Production of [2,3-²H2]malate, following injection of [2,3-²H2]fumarate (1 g/kg) into tumor-bearing mice, was measured in a murine lymphoma (EL4) treated with etoposide, and in human breast (MDA-MB-231) and colorectal (Colo205) xenografts treated with a TRAILR2 agonist, using surface-coil localized ²H MR spectroscopy at 7 T. Malate production was also imaged in EL4 tumors using a fast ²H chemical shift imaging sequence. The malate/fumarate ratio increased from 0.016 ± 0.02 to 0.16 ± 0.14 in EL4 tumors 48 h after drug treatment (P = 0.0024, n = 3), and from 0.019 ± 0.03 to 0.25 ± 0.23 in MDA-MB-231 tumors (P = 0.0001, n = 5) and from 0.016 ± 0.04 to 0.28 ± 0.26 in Colo205 tumors (P = 0.0002, n = 5) 24 h after drug treatment. These increases were correlated with increased levels of cell death measured in excised tumor sections obtained immediately after imaging. ²H MR measurements of [2,3-²H2]malate production from [2,3-²H2]fumarate provide a potentially less expensive and more sensitive method for detecting cell death in vivo than 13C MR measurements of hyperpolarized [1,4-13C2]fumarate metabolism, which have been used previously for this purpose. [ABSTRACT FROM AUTHOR]