Amino acid compositions of human hair fibrous protein components purified with two-dimensional electrophoresis

Insights into the Passive Partitioning of Amino Acids and Codeine into Human Hair

Background:

Cells that form hair are among the body's most rapidly dividing cells, with each daughter cell becoming part of the hair shaft as it differentiates and lengthens. It follows that hair might contain concentrations of xenobiotics (environmental chemicals, therapeutic drugs, illicit substances, etc.) reflective of the concentration in blood at the time of division and onset of differentiation of cells that give rise to hair.

Objective:

This study was designed to gain insight into the passive incorporation of xenobiotics into hair.

Methods:

This study focused on the parameters of the passive partitioning of three agents, two water-soluble amino acids (cysteine and glutamine) and codeine into hair. Undamaged black hair from various ethnic groups was incubated in solutions containing the three agents as a function of time and concentration. Hair was washed extensively; time and dose to steady state as well as partitioning coefficients were determined for each agent. Codeine washing with a pH gradient also was carried out.

Results:

Data show that the partitioning coefficient of the agents is linear but not stoichiometric. At low doses passive partitioning into hair is efficient, a 1 minute exposure leading to significant retention. Washing extensively with deionized water, the fluid used for passive partitioning of the test agent, will not reversibly extract all of the agent, regardless of race.

Conclusion:

Hair can effectively absorb and retain agents of the environment, and this retention occurs via mechanisms other than those inherent to an ion exchange column.

Structural model of an antistasin/notch-like fusion protein from the cocoon wall of the aquatic leech, Theromyzon tessulatum

The aquatic leech, Theromyzon tessulatum, secretes a proteinaceous cocoon with extraordinary physical properties (e.g., proteolytic, thermal resiliency). The deduced amino acid sequence of a major protein (Tcp-Theromyzon cocoon protein) from the T. tessulatum cocoon wall has been used to model the endogenous structure of the Tcp protein. The Tcp protein sequence comprises six internal repeats, each containing 12 ordered Cys residues. Amino acid alignments suggest that the region Cys1-->6 is homologous to antistasin, a leech anticoagulant, and Cys7-->12 is homologous to an epidermal growth factor-like domain found in notch-class proteins, which play critical roles in development, signaling, and adhesion throughout the Animalia. Modeling of individual domains (i.e., antistasin and notch) positions multiple hydrophobic and charged residues on the surface. When the antistasin and notch domains were fused, hydrophobic pockets appeared that may facilitate a polymerization mechanism. Collectively, the predicted features of our Tcp model are consistent with the physical properties of the leech cocoon wall.

Proteome research: complementarity and limitations with respect to the RNA and DNA worlds

A methodological overview of proteome analysis is provided along with details of efforts to achieve high-throughput screening (HTS) of protein samples derived from two-dimensional electrophoresis gels. For both previously sequenced organisms and those lacking significant DNA sequence information, mass spectrometry has a key role to play in achieving HTS. Prototype robotics designed to conduct appropriate chemistries and deliver 700-1000 protein (genes) per day to batteries of mass spectrometers or liquid chromatography (LC)-based analyses are well advanced, as are efforts to produce high density gridded arrays containing > 1000 proteins on a single matrix assisted laser desorption ionisation/time-of-flight (MALDI-TOF) sample stage. High sensitivity HTS of proteins is proposed by employing principally mass spectrometry in an hierarchical manner: (i) MALDI-TOF-mass spectrometry (MS) on at least 1000 proteins per day; (ii) electrospray ionisation (ESI)/MS/MS for analysis of peptides with respect to predicted fragmentation patterns or by sequence tagging; and (iii) ESI/MS/MS for peptide sequencing. Genomic sequences when complemented with information derived from hybridisation assays and proteome analysis may herald in a new era of holistic cellular biology. The current preoccupation with the absolute quantity of gene-product (RNA and/or protein) should move backstage with respect to more molecularly relevant parameters, such as: molecular half-life; synthesis rate; functional competence (presence or absence of mutations); reaction kinetics; the influence of individual gene-products on biochemical flux; the influence of the environment, cell-cycle, stress and disease on gene-products; and the collective roles of multigenic and epigenetic phenomena governing cellular processes. Proteome analysis is demonstrated as being capable of proceeding independently of DNA sequence information and aiding in genomic annotation. Its ability to confirm the existence of gene-products predicted from DNA sequence is a major contribution to genomic science. The workings of software engines necessary to achieve large-scale proteome analysis are outlined, along with trends towards miniaturisation, analyte concentration and protein detection independent of staining technologies. A challenge for proteome analysis into the future will be to reduce its dependence on two-dimensional (2-D) gel electrophoresis as the preferred method of separating complex mixtures of cellular proteins. Nonetheless, proteome analysis already represents a means of efficiently complementing differential display, high density expression arrays, expressed sequence tags, direct or subtractive hybridisation, chromosomal linkage studies and nucleic acid sequencing as a problem solving tool in molecular biology.

Two-dimensional polyacrylamide gel electrophoresis of human hair matrix proteins using isoelectric focusing electrophoresis as the first dimension

S-carboxymethylated (SCM) matrix proteins from fifteen normal human scalp hair specimens were analyzed using two-dimensional polyacrylamide gel electrophoresis (PAGE) with usual isoelectric focusing electrophoresis as the first dimension and then with usual sodium dodecyl sulfate-PAGE as the second dimension. On the electrophoregrams obtained, one low-mobility smear of SCM proteins embedding one SCM protein band was always seen. Many higher-mobility SCM protein spots were also always seen. However, some variations were seen in these SCM protein compositions; in type I, there were eighteen SCM protein components and, in type II, seventeen components.