A nucleotide insertion and frameshift cause albumin Kénitra, an extended and O-glycosylated mutant of human serum albumin with two additional disulfide bridges

Albumin Kenitra is a new type of genetic variant of human serum albumin that has been found in two members of a family of Sephardic Jews from Kenitra (Morocco). The slow-migrating variant and the normal protein were isolated by anion-exchange chromatography and, after treatment with CNBr, the digests were analyzed by two-dimensional electrophoresis in a polyacrylamide gel. The CNBr peptides of the variant were purified by reverse-phase high performance liquid chromatography and submitted to sequence analysis. Albumin Kenitra is peculiar because it has an elongated polypeptide chain, 601 residues instead of 585, and its sequence is modified beginning from residue 575. DNA structural studies showed that the variant is caused by a single-base insertion, an adenine at nucleotide position 15 970 in the genomic sequence, which leads to a frameshift with the subsequent translation to the first termination codon of exon 15. Mass spectrometric analyses revealed that the four additional cysteine residues of the variant form two new S-S bridges and showed that albumin Kenitra is partially O-glycosylated by a monosialylated HexHexNAc structure. This oligosaccharide chain has been located to Thr596 by amino-acid sequence analysis of the tryptic fragment 592-59

Albumin-based cancer therapeutics for intraperitoneal drug delivery : a review

Albumin is a remarkable carrier protein with multiple cellular receptor and ligand binding sites, which are able to bind and transport numerous endogenous and exogenous compounds. The development of albumin-bound drugs is gaining increased importance in the targeted delivery of cancer therapy. Intraperitoneal (IP) drug delivery represents an attractive strategy for the local treatment of peritoneal metastasis (PM). PM is characterized by the presence of widespread metastatic tumor nodules on the peritoneum, mostly originating from gastro-intestinal or gynaecological cancers. Albumin as a carrier for chemotherapy holds considerable promise for IP delivery in patients with PM. Data from recent (pre)clinical trials suggest that IP albumin-bound chemotherapy may result in superior efficacy in the treatment of PM compared to standard chemotherapy formulations. Here, we review the evidence on albumin-bound chemotherapy with a focus on IP administration and its efficacy in PM

Distribution of Brevetoxin (PbTx-3) in Mouse Plasma: Association with High-Density Lipoproteins

We investigated the brevetoxin congener PbTx-3 to determine its distribution among carrier proteins, including albumin and blood lipoproteins. Using a radiolabeled brevetoxin tracer (PbTx-3), we found that 39% of the radiolabel remained associated with components in mouse plasma after > 15 kDa cutoff dialysis. Of this portion, only 6.8% was bound to serum albumin. We also examined the binding of brevetoxin to various lipoprotein fractions. Plasma, either spiked with PbTx-3 or from mice treated for 30 min with PbTx-3, was fractionated into different-sized lipoproteins by iodixanol gradient ultracentrifugation. Each fraction was then characterized and quantified by agarose gel electrophoresis and brevetoxin radioimmunoassay, respectively. In both the in vitro and in vivo experiments, the majority of brevetoxin immunoreactivity was restricted to only those gradient fractions that contained high-density lipoproteins (HDLs). Independent confirmation of brevetoxin binding to HDLs was provided by high molecular weight (100 kDa cutoff) dialysis of [(3)H]PbTx-3 from lipoprotein fractions as well as a scintillation proximity assay using [(3)H]PbTx-3 and purified human HDLs. This information on the association of brevetoxins with HDLs provides a new foundation for understanding the process by which the toxin is delivered to and removed from tissues and may permit more effective therapeutic measures to treat intoxication from brevetoxins and the related ciguatoxins

Excited State Interactions in Flurbiprofen-Tryptophan dyads

This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry B, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/jp071301z[EN] Fluorescence and laser-flash photolysis measurements have been performed on two pairs of diastereomeric dyads that contain the nonsteroidal anti-inflammatory drug (S)- or (R)-flurbiprofen (FBP) and (S)-tryptophan (Trp), which is a relevant amino acid present in site I of human serum albumin. The fluorescence spectra were obtained when subjected to excitation at 266 nm, where similar to 60% of the light is absorbed by FBP and similar to 40% is absorbed by Trp; the most remarkable feature observed in all dyads was a dramatic fluorescence quenching, and the residual emission was assigned to the Trp chromophore. In addition, an exciplex emission was observed as a broad band between 380 and 500 nm, especially in the case of the (R,S) diastereomers. The fluorescence lifetimes (tau(F)) at lambda(em) = 340 nm were clearly shorter in the dyads than in Trp-derived model compounds; in contrast, the values of tau(F) at lambda(em) = 440 nm (exciplex) were much longer. On the other hand, the typical FBP triplet-triplet transient absorption spectrum was obtained when subjected to laser-flash photolysis, although the signals were less intense than when FBP was directly excited under the same conditions. The main photophysical events in FBP-Trp dyads can be summarized as follows: (1) most of the energy provided by the incident radiation at 266 nm reaches the excited singlet state of Trp ((1)Trp*), either via direct absorption by this chromophore or by singlet singlet energy transfer from excited FBP ((FBP)-F-1*); (2) a minor, yet stereoselective deactivation of (FBP)-F-1* leads to detectable exciplexes and/or radical ion pairs; (3) the main process observed is intramolecular (1)Trp* quenching; and (4) the first triplet excited-state of FBP can be populated by triplet-triplet energy transfer from excited Trp or by back-electron transfer within the charge-separated states.Financial support from the MCYT (CTQ2004-03811) and the Generalitat Valenciana (GV06/099) is gratefully acknowledged. Author I.V. thanks MEC for a fellowship.Vayá Pérez, I.; Jiménez Molero, MC.; Miranda Alonso, MÁ. (2007). Excited State Interactions in Flurbiprofen-Tryptophan dyads. The Journal of Physical Chemistry B. 111(31):9363-9371. https://doi.org/10.1021/jp071301zS936393711113