Monosaccharides configurations (alpha beta, D L) identification I am really finding it difficult to identify the correct configuration(s) of a given monosaccharide, in fact my friends and I have been trying to solve this, much to our annoyance. 

In one of our classes, our teacher said, in cyclic form:


  If $\ce{CH2OH}$ is below the ring its configuration is  L, and if its above the ring its D.
   If $\ce{C1}$'s $\ce{OH}$ is below the ring its alpha configuration and if its above its beta configuration .


My friends seem to agree with the above explanation, however my understanding is:


  If all groups of $\ce{OH}$ and $\ce{-CH2OH}$ is reversed from D form, its L.
  If $\ce{C1}$'s $\ce{OH}$ is on the same side of the ring as $\ce{-CH2OH}$ its beta else its
  alpha.


So I want to know if these assumptions are right:


D and L in linear form:


If the last chiral carbon's OH (one before the last carbon) is on the right its D and if its on the left its L. so if you want to make for example L glucose from D, you should reverse ALL groups.  

D and L in cyclic form:


It's hard mainly but can be deduced by making linear form into cyclic and cyclic into linear and comparing them or reversing all carbon branches.

Alpha and Beta in cyclic form:


If the carboxyl carbon's $\ce{OH}$ is on the same side of last ring carbons branch ($\ce{CH2OH}$ in glucose, $\ce{COO-}$ in glucoronate) it's neta, else it's alpha. So in D form, if $\ce{OH}$ is above it's beta else it is alpha. In L form, if $\ce{OH}$ is above its alpha else its beta.



Also when i see 3D linear form of Glucose it doesn't match with 2D at all: 2D view of this site isn't like what I find in books I can't find the match between 2D and 3D view neither.



I'm still confused because of following examples:

1-Alpha-L-Glucose


2-Alpha-D-Glucose


3-Beta-D-Glucuronate


4-Beta-L-Iduronic Acid


these just don't match.

also Harper biochemistry image is this:


but lehningers is this:
It’s easy to understand your frustrations, however you need to understand the basic stereochemistry and conformations of sugars.

A monosaccharide is designated D if the hydroxyl group on the highest numbered asymmetric carbon is drawn to the right in a Fischer projection, as in D-glyceraldehyde:



Note that the designation D or L merely relates the configuration of a given molecule to that of glyceraldehyde and does not specify the sign of rotation of plane-polarized light.

As I covered this explanation already on one of my posts:Are glucose and galactose cis-trans isomers of each other?


  D sugars have the same absolute configuration at the asymmetric
  center farthest removed from their carbonyl group as does
  D-glyceraldehyde. The L sugars, in accordance with this convention,
  are mirror images of their D counterparts


Cyclic forms

The designation α indicates that the hydroxyl group at the anomeric center (hemiacetal or hemiketal carbon)  is, in a Fischer projection, on the same side as the hydroxyl attached at the farthest chiral center, whereas  β indicates that these hydroxyl groups are on opposite sides:



In the α anomer, the $\ce{OH}$ substituent to the anomeric carbon is on the opposite side of the sugar ring from the $\ce{CH2OH}$ group at the chiral center that designates the D or L configuration ($\ce{C5}$ in hexoses). The other anomer is known as the β form.

The Haworth projections represent the stereochemistry of sugars more realistically than do the Fischer projections, which is why they are preferred:

For a D sugar, any group that is written to the right of the carbon in a Fischer projection has a downward direction in a Haworth projection; any group that is written to the left in a Fischer projection has an upward direction in a Haworth projection.

The terminal $\ce{-CH2OH}$ group, which contains the carbon atom with the highest number in the numbering scheme, is shown in an upward direction.


  Similarly  in the  α-anomer, the hydroxyl on the anomeric carbon is on the opposite side of the ring from the terminal $\ce{-CH2OH}$ group (i.e., pointing down). In the β-anomer, it is on the same side of the ring (pointing up).






References


Lehninger Principles of Biochemistry 
Voet and Voet biochemistry
Biochemistry Grisham
Biochemistry Campbell and Farrel